Academic literature on the topic 'In-Plane nanowires'
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Journal articles on the topic "In-Plane nanowires"
1
Belim, Sergey V., and Igor V. Bychkov. "Magnetic Properties of 2D Nanowire Arrays: Computer Simulations." Materials 16, no. 9 (April 27, 2023): 3425. http://dx.doi.org/10.3390/ma16093425.
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The paper considers a nanowires 2D array located in the nodes of a square lattice. Computer simulations use the Heisenberg model and Metropolis algorithm. The array consists of small nanowires that are monodomain. The exchange interaction orders the spins within a single nanowire. Dipole–dipole forces act between neighboring nanowires. The shape of an individual nanowire affects its magnetic anisotropy. Computer simulations examine the phase transition temperature and magnetization behavior of the system. The type of magnetic moments ordering in the array of nanowires depends on the orientation of their long axis. We consider two types of systems. The nanowires’ long axes are oriented perpendicular to the plane of their location in the first case. A dipole–dipole interaction results in first-type superantiferromagnetic ordering of the nanowires’ magnetic moments for such orientation. The nanowires’ long axes are oriented in the plane of the system in the second case. Dipole–dipole interaction results in second-type superantiferromagnetic ordering in such systems. The dependence of the phase transition temperature on the dipole–dipole interaction intensity is investigated.
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Castillo-Sepúlveda, Sebastián, Rosa M. Corona, Eduardo Saavedra, David Laroze, Alvaro P. Espejo, Vagson L. Carvalho-Santos, and Dora Altbir. "Nucleation and Stability of Toron Chains in Non-Centrosymmetric Magnetic Nanowires." Nanomaterials 13, no. 12 (June 7, 2023): 1816. http://dx.doi.org/10.3390/nano13121816.
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This work analyzes the magnetic configurations of cylindrical nanowires with a bulk Dzyaloshinskii–Moriya interaction and easy-plane anisotropy. We show that this system allows the nucleation of a metastable toron chain even when no out-of-plane anisotropy exists in the nanowire’s top and bottom surfaces, as usually required. The number of nucleated torons depends on the nanowire length and the strength of an external magnetic field applied to the system. The size of each toron depends on the fundamental magnetic interactions and can be controlled by external stimuli, allowing the use of these magnetic textures as information carriers or nano-oscillator elements. Our results evidence that the topology and structure of the torons yield a wide variety of behaviors, revealing the complex nature of these topological textures, which should present an exciting interaction dynamic, depending on the initial conditions.
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Diao, Yu, Lei Liu, Sihao Xia, and Yike Kong. "Differences in optoelectronic properties between H-saturated and unsaturated GaN nanowires with DFT method." International Journal of Modern Physics B 31, no. 12 (May 10, 2017): 1750084. http://dx.doi.org/10.1142/s0217979217500849.
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To investigate the influences of dangling bonds on GaN nanowires surface, the differences in optoelectronic properties between H-saturated and unsaturated GaN nanowires are researched through first-principles study. The GaN nanowires along the [0001] growth direction with diameters of 3.7, 7.5 and 9.5 Å are considered. According to the results, H-saturated GaN nanowires are more stable than the unsaturated ones. With increasing nanowire diameter, unsaturated GaN nanowires become more stable, while the stability of H-saturated GaN nanowires has little change. After geometry optimization, the atomic displacements of unsaturated and H-saturated models are almost reversed. In (0001) crystal plane, Ga atoms tend to move inwards and N atoms tend to move outwards slightly for the unsaturated nanowires, while Ga atoms tend to move outwards and N atoms tend to move inwards slightly for the H-saturated nanowires. Besides, with increasing nanowire diameter, the conduction band minimum of H-saturated nanowire moves to the lower energy side, while that of the unsaturated nanowire changes slightly. The bandgaps of H-saturated nanowires are approaching to bulk GaN as the diameter increases. Absorption curves and reflectivity curves of the unsaturated and H-saturated nanowires exhibit the same trend with the change of energy except the H-saturated models which show larger variations. Through all the calculated results above, we can better understand the effects of dangling bonds on the optoelectronic properties of GaN nanowires and select more proper calculation models and methods for other calculations.
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BERTNESS, KRIS, NORMAN SANFORD, JOHN SCHLAGER, ALEXANA ROSHKO, TODD HARVEY, PAUL BLANCHARD, MATTHEW BRUBAKER, ANDREW HERRERO, and ARIC SANDERS. "CATALYST-FREE GAN NANOWIRES AS NANOSCALE LIGHT EMITTERS." International Journal of High Speed Electronics and Systems 21, no. 01 (March 2012): 1250003. http://dx.doi.org/10.1142/s0129156412500036.
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Catalyst-free growth of GaN nanowires with molecular beam epitaxy produces material of exceptionally high quality with long minority-carrier lifetimes and low surface recombination velocity. The nanowires grow by thermodynamic driving forces that enhance the sticking coefficient of incoming reagents to the end facets of the nanowire while inhibiting growth on the m-plane sidewalls. Photoluminescence (PL) studies confirm that the material is essentially free of detrimental chemical impurities and crystalline defects. The nanowires are readily excited to lasing with modest optical pump power. Recent progress in methods for selective epitaxy has made it possible to control both the diameter and placement of the nanowires. Despite the high material quality, the energy-conversion efficiency of single nanowire LEDs remains low. The primary limitation appears to be optimizing the p-type doping with Mg , which is both a growth and a measurement problem.
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Дубровский, В. Г., and И. В. Штром. "Кинетика роста планарных нитевидных нанокристаллов." Письма в журнал технической физики 46, no. 20 (2020): 15. http://dx.doi.org/10.21883/pjtf.2020.20.50149.18440.
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A kinetic equation is obtained which describes the elongation rate of planar semiconductor nanowires growing via the vapor-liquid-solid mechanism in the substrate plane. Theoretical analysis of different regimes depending on the nanowire radius and epitaxial conditions shows that planar growth of nanowires can be limited by either the Gibbs-Thomson effect in a catalyst droplet (for small droplet size) or surface diffusion of adatoms (for larger nanowire radii. Diffusion-like dependence of the growth rate on the nanowire radius R has the form R^(-m), where the power exponent equal 1, 3/2 or 2 depending on the mechanism of surface diffusion transport.
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Zou, J., and X. F. Li. "Effect of the Casimir Force on Buckling of a Double-Nanowire System with Surface Effects." International Journal of Structural Stability and Dynamics 18, no. 10 (October 2018): 1850118. http://dx.doi.org/10.1142/s0219455418501183.
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Structural stability of a double-nanowire system with surface effects subjected to axial compressive forces is analyzed. Taking into account the Casimir force between the two nanowires, two coupled governing equations for buckling of a double-nanowire system are derived. For four typical end supports including simply-supported, clamped, cantilevered, and clamped-pinned double-nanowire systems, the characteristic equations are derived and the critical loads are determined for the out-of-phase in-plane buckling. Numerical results indicate that positive surface elasticity enhances the load-carrying capacity of the nanowires, and the reverse is also true. The Casimir force and residual surface tension always increase the critical loads.
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Hong, Ie-Hong, and Sheng-Wen Liu. "Observation of the Magnetization Reorientation in Self-Assembled Metallic Fe-Silicide Nanowires at Room Temperature by Spin-Polarized Scanning Tunneling Spectromicroscopy." Coatings 9, no. 5 (May 10, 2019): 314. http://dx.doi.org/10.3390/coatings9050314.
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The quasi-periodic magnetic domains in metallic Fe-silicide nanowires self-assembled on the Si(110)-16 × 2 surface have been observed at room temperature by direct imaging of both the topographic and magnetic structures using spin-polarized scanning tunneling microscopy/spectroscopy. The spin-polarized differential conductance (dI/dV) map of the rectangular-sectional Fe-silicide nanowire with a width and height larger than 36 and 4 nm, respectively, clearly shows an array of almost parallel streak domains that alternate an enhanced (reduced) density of states over in-plane (out-of-plane) magnetized domains with a magnetic period of 5.0 ± 1.0 nm. This heterostructure of magnetic Fe-silicide nanowires epitaxially integrated with the Si(110)-16 × 2 surface will have a significant impact on the development of Si-based spintronic nanodevices.
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Zhao, S., L. Clime, K. Chan, F. Normandin, H. Roberge, A. Yelon, R. W. Cochrane, and T. Veres. "Statistical Study of Effective Anisotropy Field in Ordered Ferromagnetic Nanowire Arrays." Journal of Nanoscience and Nanotechnology 7, no. 1 (January 1, 2007): 381–86. http://dx.doi.org/10.1166/jnn.2007.18039.
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Soft ferromagnetic nanowire arrays were obtained by electrodeposition of Co–Fe–P alloy into the pores of high quality home-made anodized aluminum oxide (AAO) templates. Bath acidity and current density were the two parameters used in order to tailor the orientation of local anisotropy axes in individual nanowires. In order to quantify the influence of the induced anisotropies on the magnetization processes in individual nanowires, the in-plane magnetization loops of the arrays are modeled as log-normal distributions of Stoner-Wohlfarth transverse magnetization processes. Using the lognormal mean parameter as an approximation for the saturation applied field of the array, we compute the effective anisotropy of the nanowires, which is found to increase with the pH of the electrodeposition bath.
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Wang, Jingchun, Floriano Cuccureddu, Rafael Ramos, Cormac Ó. Coileáin, Igor V. Shvets, and Han-Chun Wu. "Magnetoresistance of Nanoscale Domain Walls Formed in Arrays of Parallel Nanowires." SPIN 09, no. 01 (March 2019): 1950004. http://dx.doi.org/10.1142/s2010324719500048.
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We present the possibility of enhancing magnetoresistance (MR) by controlling nanoscale domain wall (DW) width in a planar nanowire array. Results based on micromagnetic calculations show that DW width decreases with increasing exchange bias field and decreases with reducing exchange interaction between neighboring nanowires. Fe/Fe3O4 nanowire arrays were grown on [Formula: see text]-plane sapphire to demonstrate the feasibility of this concept, and an enhanced MR ratio of 3.7% was observed at room temperature. compared with flat and stepped Fe3O4 thin films.
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Giraldo-Daza, Helver Augusto, José Darío Agudelo-Giraldo, César Leandro Londoño-Calderón, and Henry Reyes-Pineda. "Structural Disorder of CuO, ZnO, and CuO/ZnO Nanowires and Their Effect on Thermal Conductivity." Crystals 13, no. 6 (June 15, 2023): 953. http://dx.doi.org/10.3390/cryst13060953.
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In this work, the structural defects and the thermal conductivity of CuO, ZnO, and CuO/ZnO nanowires have been studied, using molecular dynamics simulation with COMB3 potential. The initial parameters and atoms positions were taken from reports of bulk materials with tenorite and wurtzite structures, respectively. Nanowires were grown along the c-axis, as observed experimentally. The results confirm the defects apparition in the systems after simulation with a formation of grains to reduce the energy of the nanowires. In the CuO nanowires case, the lack of periodicity in the basal plane causes a contraction effect over the network parameter b of the monoclinic structure with a Cu-O distance reduction. [A constriction effect on inclined planes, as a product of surface charges, deforms the nanowire, generating undulations. In ZnO nanowires, a decrease in the Zn-Zn distance produced a contraction in the nanowire length. A constriction effect was evident on the surface charges. It presented a bond reduction effect, which was larger at the ends of the nanowire. In CuO/ZnO nanowires, the structural defects come from the distortions of the crystalline lattice of the ZnO rather than CuO. The thermal conductivity of the nanowires was calculated at temperatures between 200 K and 600 K using the Green–Kubo equation. Results showed similar values to those reported experimentally, and the characteristic maximum with similar trends to those observed in semiconductors. Our results suggest that structural defects appear in nanowires grown on the free substrate, and are not related to the lattice mismatch.
Dissertations / Theses on the topic "In-Plane nanowires"
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Fan, Zheng. "Study of in-plane silicon nanowires obtained via a solid-liquid-solid growth process and their self-organization for electronic applications." Palaiseau, Ecole polytechnique, 2015. http://www.theses.fr/2015EPXX0117.
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Khelifi, Wijden. "Selective Growth and Characterization of InAs and InSb Nanostructures." Electronic Thesis or Diss., Université de Lille (2022-....), 2024. http://www.theses.fr/2024ULILN001.
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Les composés d'arséniure et d'antimoniure d'indium figurent parmi les candidats les plus prometteurs pour la conception de dispositifs quantiques, grâce à leurs propriétés électroniques supérieures telles que la haute mobilité des électrons et leur fort couplage spin-orbite. Cependant, leur déploiement est souvent entravé par le désaccord de maille qu'ils possèdent avec les substrats III-V conventionnels et qui les rend défectueux. Cette thèse propose une solution pour fabriquer des nanostructures d'InAs et d'InSb de bonne qualité, grâce à une croissance sélective par épitaxie par jets moléculaires dans des ouvertures de SiO2.Une étude structurale et morphologique de couches bi-dimensionnelles et de nanofils d'InAs et InSb sur des substrats de GaAs ou d'InP orientés suivant les directions [001] et [111] a été réalisée. L'optimisation des paramètres de croissance a conduit à la fabrication de nanostructures planaires continues et facettées avec une minimisation des défauts émergents. Ces systèmes ont ensuite été étudiés par microscopie à effet tunnel à quatre pointes en ultravide, technique qui permet de s'astreindre de la fabrication d'électrodes pour caractériser les propriétés de transport. La comparaison du transport dans des nanofils InAs reconstruits en surface et des nanofils cœur-coquille InAs/GaSb a révélé l'intérêt d'une encapsulation des nanofils d'InAs pour augmenter sensiblement la mobilité électronique dans les nanofils.Contrairement aux nanofils d'InAs, qui peuvent être protégés par une fine couche d'arsenic pour éviter l'oxydation de leur surface pendant leurs transferts à l'air, il n'existe pas de protection efficace pour l'InSb. Aussi, la dernière partie de la thèse porte sur la caractérisation de la désoxydation des surfaces d'InSb (001) et (111) en combinant la spectroscopie Raman et la microscopie à effet tunnel. Cette dernière étude ouvre la voie à des mesures ultérieures de transport de nanofils InSb par microscopie à effet tunnel à quatre pointes.En conclusion, la qualité structurale et électronique des nanofils d'InAs et InSb réalisée dans ce travail est compatible avec le régime de transport balistique. Ces résultats jettent les bases pour la fabrication de structures III-V plus complexes actuellement recherchées pour la conception de dispositifs quantiquesIn the landscape of electronic device fabrication, the semiconductor compounds indium arsenide (InAs) and indium antimonide (InSb) have emerged as materials of significant interest for high-speed telecommunications and infrared optoelectronics. More recently, their excellent electron transport characteristics, characterized by high mobility and strong spin-orbit coupling, render them highly conducive for applications that exploit quantum transport phenomena. However, their deployment is often hampered by the lattice mismatch they possess with conventional III-V substrates, making them defective. This thesis proposes a solution for fabricating good-quality in-plane InAs and InSb nanostructures, using selective area growth by molecular beam epitaxy in SiO2 apertures.A structural and morphological study of InAs and InSb two-dimensional layers and nanowires on GaAs and InP substrates oriented along the [001] and [111] directions has been carried out. The optimization of the growth parameters led to the fabrication of continuous and faceted planar nanostructures with minimized threading defects. These systems were then studied by four-tip scanning tunnelling microscopy in ultra-high vacuum, a technique that eliminates the need for electrode fabrication to characterize the transport properties. The comparison of transport in surface-reconstructed InAs nanowires and core-shell InAs/GaSb nanowires revealed the benefits of embedding the InAs nanowires to significantly increase the electron mobility in the nanowires.Unlike the InAs nanowires, which can be protected by a thin layer of arsenic to preventtheir surface oxidation during their transfer to air, there is no effective protection for InSb.The final part of the thesis therefore focuses on characterizing the deoxidation of InSb (001) and (111) surfaces using a combination of Raman spectroscopy and scanning tunnelling microscopy. This latter study paves the way for subsequent measurements of the transport in InSb nanowires by four-tip scanning tunnelling microscopy.In conclusion, the structural and electronic quality of the InAs and InSb nanowires produced in this work is compatible with the ballistic transport regime. These results lay down the foundations for the fabrication of the more complex III-V structures, highly prized for thedesign of quantum devices
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Dias, Mariama Rebello de Sousa. "Transport phenomena in quasi-one-dimensional heterostructures." Universidade Federal de São Carlos, 2014. https://repositorio.ufscar.br/handle/ufscar/4973.
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Previous issue date: 2014-02-21Universidade Federal de Sao Carlos
O crescimento e caracterização de sistemas de heteroestruturas semicondutoras quasi-unidimensionais têm atraído grande interesse devido à sua potencial de aplicação tecnológica, como foto-detectores, dispositivos opto-eletrônicos assim como seu para o processamento de informação quântica e aplicações em fotônica. O objetivo desta tese é o estudo das propriedades de transporte eletrônico e de spin em sistemas semicondutores quasi-unidimensionais, especificamente trataremos de nanofios (NWs) homogêneos, NWs acoplados, NWs do tipo plano-geminado (TP), diodos de tunelamento ressonante (ETD) e cadeias de pontos quânticos (QDCS). Escolhemos o método k-p, particularmente o Hamiltoniano de Luttinger, para descrever os efeitos de confinamento e tensão biaxial. Este sugeriu uma modulação do caráter do estado fundamental que, complementada com a dinâmica fônons fornecidas pelas simulações da Dinâmica Molecular (MD), permitiu a descrição da modulação da mobilidade de buracos por emissão ou absorção de fônons. Em relação ao sistema de NWs acoplado,estudamos, através do método da matriz de transferência (TMM), as propriedades de transporte de elétrons e spin sob a interação de spin-órbita (SOI) de Eashba, localizada na região de acoplamento entre fios. Foram consideradas várias configurações de tensões de gate (Vg) aplicadas nos fios. Desse modo, compreendemos a modulação do transporte de spin quando esse é projetado no direção-z através da combinação do SOI e das dimensionalidades do sistema. Da mesma forma, a combinação de SOI e da Vg aplicada deu origem a modulação da polarização, quando o spin medido é projetado na mesma direção em que o SOI de Eashba atua, a direção y. Usando o TMM, exploramos as propriedades de transporte de um DBS e o efeito de uma resistência em série com o intuito de provar a natureza da biestabilidade das curvas características I V bem como o aumento de sua área com temperatura, resultados fornecidos por experimentos. O modelo indicou que aumentando da resistência pela diminuição sa temperatura aumenta a área biestável. A presença de uma hetero-junção adicional ao sistema induz uma densidade de carga nas suas interfaces. De acordo com esta configuração, a queda de tensão total do ETDS muda, podendo ser confirmada experimentalmente. A formação dos peculiares campos de deformação e sua influência sobre a estrutura eletrônicas e propriedades de transporte em superredes de TP foi estudada sistematicamente. Assim, as propriedades de transporte, de ambos os elétrons e buracos, pode ser sintonizada eficientemente, mesmo no caso de elétrons r em sistemas de blenda de zinco, contrastando com a prevista transparência de elétrons r em superredes de semicondutores III-V heteroestruturados. Além disso, constatamos que a probabilidade de transmissão para buracos da banda de valência também poderia ser efetivamente modificada através de uma tensão externa.Por fim, colaboradores sintetizaram com sucesso sistemas de QDCs de InGaAs através da epitaxia de feixe molecular e engenharia de tensão. Um comportamento anisotrópico da condutância com a temperatura foi observado em QDCs com diferentes concentrações de dopagem, medida realizada ao longo e entre os QDCs. O modelo teórico 1D de hoppíng desenvolvido mostrou que a presença de estados OD modela a resposta anisotrópica da condutância neste sistemas.
The growth and characterization of semiconductor quasi-one-dimensional heterostructure systems have attracted increasing interest due to their potential technological application, like photo-detectors, optoelectronic devices and their promising features for quantum information processing and photonic applications. The goal of this thesis is the study of electronic and spin transport properties on quasi-one-dimensional semiconductor systems; specifically, homogenous nanowires (NWs), coupled NW s, twin-plane (TP) NWs, resonant tunneling diodes (RTDs), and quantum dot chains (QDCs). The k-p method, in particular the Luttinger Hamiltonian, was chosen to describe the effects of biaxial confinement and strain. This suggested a modulation of the ground state character that, complemented with the phonon dynamics provided by Molecular Dynamics (MD) simulations, allowed the description of the hole mobility modulation by either phonon emission or absorption. Regarding the coupled NW s system, the electron and spin transport properties affected by a Rashba spin-orbit interaction (SOI) at the joined region were unveiled through the Transfer Matrix Method (TMM). Various configurations of gate voltages (Vg), applied on the wire structure, were considered. We were able to understand the modulation of the spin transport projected in the z-direction trough the combination of the SOI and the system dimensionalities. Likewise, the combination of SOI and applied Vg gave rise to a modulation of the polarization, when the measured spin is projected in the same direction where the Rashba SOI acts, the y-direction. The transport properties of a DBS and the effect of a resistance in series was explored within the TMM to prove the nature of a bistability of the I V characteristics and its enhanced area with temperature provided by the experiment. The model indicates that increasing the resistente by decreasing the temperature, the bistable area enhances. The presence of an additional heterojunction induces a sheet charge at its interfaces. Under this configuration, the total voltage drop of the RTD changes and can be confirmed experimentally.The formation of the peculiar strain fields and their influence on the electronic structure and transport properties of a TP superlattice was systematically studied. Hence, the transport properties of both electrons and holes could be effectively tuned even in the case of T-electrons of zincblende systems, contrasting to the predicted transparency of T-electrons in heterolayered III-V semiconductor superlattices. Also, the transmission probability for holes at valence band could also be effectively modified by applying an external stress. Finally, using molecular-beam-epitaxy and skillful strain engineering, systems of In-GaAs QDCs were successfully synthesized by collaborators. The QDCs with different doping concentrations showed an anisotropic behavior of the conductance, measured along and across the QDCs, with temperature. The theoretical ID hopping model developed found that the presence of OD states shapes the anisotropic response of the conductance in this system.
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Vineeth, Mohanan P. "Spin Hall Effect Mediated Current Induced Magnetization Reversal in Perpendicularly Magnetized Pt/Co/Pt Based Systems." Thesis, 2016. http://etd.iisc.ac.in/handle/2005/3078.
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In the present thesis, magnetization reversal in both out-of-plane and in-plane magnetized thin lms and in devices fabricated out of those lms are explored. Pt/Co/Pt stacks with ultrathin Co layer were in-estimated initially for understanding their magnetic properties in this thesis. These perpendicular magnetized systems are good candidates for magnetic hard disc drives due to their large anisotropy, which may allow miniaturization of magnetic data storage devices. The spin Hall e ect mediated current-induced magnetization reversal in patterned Pt/Co/Pt devices were extensively investigated. Investigation of the magnetization reversal by means of a current instead of a magnetic eld is necessary to explore the possibilities of solid state magnetic memory devices. This is the primary motivation behind the investigation of current-induced magnetization reversal in Pt/Co/Pt system, in this thesis. Another important proposal for magnetic data storage is the race track memory, where the domain walls separating magnetic domains (in in-plane or out-of-plane magnetized materials) are moved by using a current. This involves a great deal of understanding of the domain wall motion in Nano-conduits under applied magnetics ends, and currents and also its interaction with engineered geometrical features. In this thesis work, magnetic led-driven domain wall pinning and deepening experiments on in-plane magnetized nanowires of perm alloy were performed to un-distend this interaction and the e act of domain wall chirality.
In chapter 1, a general introduction to di errant data storage technologies and the current progress in the leg of spintronic is presented. This will highlight a perspective of this thesis work with respect to the present day research in spintronic and magnetization reversal studies.
In chapter 2, a basic background of magnetism using the micromag-netic framework is illustrated. A brief introduction to magnetic domain walls is also presented. The Landau-Lifshitz-Gilbert dynamical equation is discussed and some case studies applied to a single domain particle with uniaxial anisotropy under the effect of spin-orbit torque are illu trated. The basics of spin-orbit coupling leading to spin Hall e ect is also explain
In chapter 3, most of the essential experimental tools along with their basic working principles are described. Extensive e orts have been in-vested in designing and building the experimental tools. These include custom designs of a sputter deposition system, an ultra-high vacuum chamber for pulsed laser ablation, a magneto-optic Kerr e ect magne-tometer, a Kerr imaging system and a magneto-transport setup. All of these experimental setups have been automated, details of which are brie y discussed in this chapter. The Kerr imaging system was designed to measure hysteresis loops, observe domain wall motion and to measure domain wall velocity under applied magnetic elds and electric current. The magneto-transport setup was used for studying the domain wall pinning and depinning experiments in permalloy nanowires.
In chapter 4, the optimization process for obtaining perpendicular mag-netic anisotropy in Pt/Co/Pt lms is described. The spin reorientation transition with varying thickness of Co (from 1.5 nm down to 0.35 nm) was studied. The magnetization easy axis direction changes from in-plane to out-of-plane as the thickness of Co is reduced. The dependence of Curie temperatures of ultrathin Co lms, with thickness as low as 0.35 nm, on the underlayer Pt thickness and its crystallinity was studied in detail. The e act of Ta but err layer on the texture of the Pt lm, and on the Curie temperature of the Pt/Co/Pt system was evaluated. To gain further insight of the role of the bottom Pt/Co and the top Co/Pt interfaces, ultrathin Cu lbs were inserted at the respective interfaces, and the anisotropy and magnetization reversal behaviour of these lbs were investigated.
In chapter 5, studies on current-induced magnetization reversal in mi-corn sized wires of Pt/Co/Pt trilete is presented. The spin Hall e act assisted spin-orbit torque was used to reversibly switch the magnetization of these devices with and without the help of an external magnetic led. Since both the top and bottom layers are Pt, any contribution from Rashia e act towards spin-orbit torque could be ignored. By preparing devices with unequal top and bottom Pt thicknesses, a net spin-orbit torque could be applied to the magnetization of the Co layer. The thickness gradient/induced anisotropy in the Co layer was utilized to experimentally investigate current-induced deterministic switching. Sin-gel domain simulations with spin-orbit torque were also carried out to understand the mechanism of deterministic switching of magnetization in Pt/Co/Pt devices. This study is expected to have made sign cant contributions and to open up the possibilities of further investigation in the studies of spin-orbit torque in Pt/Co/Pt systems for solid state magnetic memory devices.
In chapter 6, magnetic led-induced reversal in systems with in-plane magnetic anisotropy is presented. Here the e act of the width of a Nanos-trip on the anisotropy of a soft magnetic material like perm alloy was in-estimated. By introducing a nucleation pad to one end of the perm alloy nanowire, a single domain wall was generated at the junction with apple-cation of a proper magnetic led sequence. This domain wall could be in-jested into the nanowire by a magnetic led and pinned at a geometrical constriction inside the nanowire. The statistics of domain wall pinning and deepening processes indicated two di errant types of domain walls involved in the reversal process. With the assistance of micro magnetic simulations the domain walls were ident end as vortex walls of di errant chirality’s. Thus the interaction of domain walls with a Nano constriction and its dependence on the chirality of domain walls are understood.
In chapter 7, a brief summary of the results obtained during the course of investigations is presented. An outlook presented at the end will help the readers of this thesis to understand the important research problems in this area and their potential future aspects.
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Vineeth, Mohanan P. "Spin Hall Effect Mediated Current Induced Magnetization Reversal in Perpendicularly Magnetized Pt/Co/Pt Based Systems." Thesis, 2016. http://hdl.handle.net/2005/3078.
Full textAbstract:
In the present thesis, magnetization reversal in both out-of-plane and in-plane magnetized thin lms and in devices fabricated out of those lms are explored. Pt/Co/Pt stacks with ultrathin Co layer were in-estimated initially for understanding their magnetic properties in this thesis. These perpendicular magnetized systems are good candidates for magnetic hard disc drives due to their large anisotropy, which may allow miniaturization of magnetic data storage devices. The spin Hall e ect mediated current-induced magnetization reversal in patterned Pt/Co/Pt devices were extensively investigated. Investigation of the magnetization reversal by means of a current instead of a magnetic eld is necessary to explore the possibilities of solid state magnetic memory devices. This is the primary motivation behind the investigation of current-induced magnetization reversal in Pt/Co/Pt system, in this thesis. Another important proposal for magnetic data storage is the race track memory, where the domain walls separating magnetic domains (in in-plane or out-of-plane magnetized materials) are moved by using a current. This involves a great deal of understanding of the domain wall motion in Nano-conduits under applied magnetics ends, and currents and also its interaction with engineered geometrical features. In this thesis work, magnetic led-driven domain wall pinning and deepening experiments on in-plane magnetized nanowires of perm alloy were performed to un-distend this interaction and the e act of domain wall chirality.
In chapter 1, a general introduction to di errant data storage technologies and the current progress in the leg of spintronic is presented. This will highlight a perspective of this thesis work with respect to the present day research in spintronic and magnetization reversal studies.
In chapter 2, a basic background of magnetism using the micromag-netic framework is illustrated. A brief introduction to magnetic domain walls is also presented. The Landau-Lifshitz-Gilbert dynamical equation is discussed and some case studies applied to a single domain particle with uniaxial anisotropy under the effect of spin-orbit torque are illu trated. The basics of spin-orbit coupling leading to spin Hall e ect is also explain
In chapter 3, most of the essential experimental tools along with their basic working principles are described. Extensive e orts have been in-vested in designing and building the experimental tools. These include custom designs of a sputter deposition system, an ultra-high vacuum chamber for pulsed laser ablation, a magneto-optic Kerr e ect magne-tometer, a Kerr imaging system and a magneto-transport setup. All of these experimental setups have been automated, details of which are brie y discussed in this chapter. The Kerr imaging system was designed to measure hysteresis loops, observe domain wall motion and to measure domain wall velocity under applied magnetic elds and electric current. The magneto-transport setup was used for studying the domain wall pinning and depinning experiments in permalloy nanowires.
In chapter 4, the optimization process for obtaining perpendicular mag-netic anisotropy in Pt/Co/Pt lms is described. The spin reorientation transition with varying thickness of Co (from 1.5 nm down to 0.35 nm) was studied. The magnetization easy axis direction changes from in-plane to out-of-plane as the thickness of Co is reduced. The dependence of Curie temperatures of ultrathin Co lms, with thickness as low as 0.35 nm, on the underlayer Pt thickness and its crystallinity was studied in detail. The e act of Ta but err layer on the texture of the Pt lm, and on the Curie temperature of the Pt/Co/Pt system was evaluated. To gain further insight of the role of the bottom Pt/Co and the top Co/Pt interfaces, ultrathin Cu lbs were inserted at the respective interfaces, and the anisotropy and magnetization reversal behaviour of these lbs were investigated.
In chapter 5, studies on current-induced magnetization reversal in mi-corn sized wires of Pt/Co/Pt trilete is presented. The spin Hall e act assisted spin-orbit torque was used to reversibly switch the magnetization of these devices with and without the help of an external magnetic led. Since both the top and bottom layers are Pt, any contribution from Rashia e act towards spin-orbit torque could be ignored. By preparing devices with unequal top and bottom Pt thicknesses, a net spin-orbit torque could be applied to the magnetization of the Co layer. The thickness gradient/induced anisotropy in the Co layer was utilized to experimentally investigate current-induced deterministic switching. Sin-gel domain simulations with spin-orbit torque were also carried out to understand the mechanism of deterministic switching of magnetization in Pt/Co/Pt devices. This study is expected to have made sign cant contributions and to open up the possibilities of further investigation in the studies of spin-orbit torque in Pt/Co/Pt systems for solid state magnetic memory devices.
In chapter 6, magnetic led-induced reversal in systems with in-plane magnetic anisotropy is presented. Here the e act of the width of a Nanos-trip on the anisotropy of a soft magnetic material like perm alloy was in-estimated. By introducing a nucleation pad to one end of the perm alloy nanowire, a single domain wall was generated at the junction with apple-cation of a proper magnetic led sequence. This domain wall could be in-jested into the nanowire by a magnetic led and pinned at a geometrical constriction inside the nanowire. The statistics of domain wall pinning and deepening processes indicated two di errant types of domain walls involved in the reversal process. With the assistance of micro magnetic simulations the domain walls were ident end as vortex walls of di errant chirality’s. Thus the interaction of domain walls with a Nano constriction and its dependence on the chirality of domain walls are understood.
In chapter 7, a brief summary of the results obtained during the course of investigations is presented. An outlook presented at the end will help the readers of this thesis to understand the important research problems in this area and their potential future aspects.
Book chapters on the topic "In-Plane nanowires"
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Ajmal Khan, M., and Yasuaki Ishikawa. "Indium (In)-Catalyzed Silicon Nanowires (Si NWs) Grown by the Vapor–Liquid–Solid (VLS) Mode for Nanoscale Device Applications." In Nanowires - Recent Progress. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.97723.
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Stacking fault free and planar defects (twin plane) free catalyzed Si nanowires (Si NWs) is essential for the carrier transport in the nanoscale devices applications. In this chapter, In-catalyzed, vertically aligned and cone-shaped Si NWs arrays were grown by using vapor–liquid–solid (VLS) mode on Si (111) substrates. We have successfully controlled the verticality and (111)-orientation of Si NWs as well as scaled down the diameter to 18 nm. The density of Si NWs was also enhanced from 2.5 μm−2 to 70 μm−2. Such vertically aligned, (111)-oriented p-type Si NWs are very important for the nanoscale device applications including Si NWs/c-Si tandem solar cells and p-Si NWs/n-InGaZnO Heterojunction LEDs. Next, the influence of substrate growth temperature (TS), cooling rate (∆TS/∆𝑡) on the formation of planar defects, twining along [112] direction and stacking fault in Si NWs perpendicular to (111)-orientation were deeply investigated. Finally, one simple model was proposed to explain the formation of stacking fault, twining of planar defects in perpendicular direction to the axial growth direction of Si NWs. When the TS was decreased from 600°C with the cooling rate of 100°C/240 sec to room temperature (RT) after Si NWs growth then the twin planar defects perpendicular to the substrate and along different segments of (111)-oriented Si NWs were observed.
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Harris, Nadine, Logan K. Ausman, Jeffrey M. McMahon, David J. Masiello, and George C. Schatz. "Computational Electrodynamics Methods." In Computational Nanoscience, 147–78. The Royal Society of Chemistry, 2011. http://dx.doi.org/10.1039/bk9781849731331-00147.
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This chapter has focused on a number of commonly used analytical and numerical electrodynamics methods that can be used to model the optical properties of plasmonic nanostructures, with emphasis on nonconventional applications of these methods to problems that have been recently been of interest in the surface spectroscopy field, especially surface-enhanced Raman scattering (SERS). A dipole reradiation (DR) methodology was added to the analytical approach of Mie theory to DR effects in SERS intensities, which is a more accurate expression for the electromagnetic enhancement theory than the commonly used plane-wave (PW) enhancement expression. We show that DR/PW differences can be significant for certain choices of detector locations due to interference and multipole effects, and generally the DR enhancements are smaller than PW. The numerical 2D finite-difference time-domain (FDTD) method was modified through the incorporation of the hydrodynamic Drude model dielectric constant, enabling the calculation of spatially nonlocal dielectric responses for arbitrarily shaped nanostructures. Nonlocal effects become important when structural features extend below around 10 nm where the dielectric constant becomes a function of both the wavevector and the frequency. The importance of including nonlocal effects was demonstrated by calculating the optical response of cylindrical and triangular nanowires. The discrete dipole approximation (DDA) provides an alternative method for determining nanoparticle optical properties that uses a similar grid to FDTD, but with different convergence characteristics. We show that for cube-shaped particles the two methods have similar convergence behavior, but accuracy is a problem for DDA, while representing the frequency dependence dielectric constant is a problem for FDTD. A general many-body formalism describing plasmon-enhanced linear spectroscopies was developed by linking the numerical DDA method with electronic structure theory based on Q-Chem. This methodology allows the calculation of the linear-response and scattering properties between a molecule, which is described quantum mechanically, interacting with a classically described metal nanostructure. To demonstrate this formalism the linear response and scattering of a pyridine–Ag spheroidal system was calculated as a function of excitation energy and aspect ratio.
Conference papers on the topic "In-Plane nanowires"
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Malakooti, Mohammad H., Hyun-Sik Hwang, and Henry A. Sodano. "Vibration Damping Enhancement in Hybrid Carbon Fiber Composites With Zinc Oxide Nanowire Interphase." In ASME 2014 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/smasis2014-7451.
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Traditional composite materials invented to be used in structures with the purpose of high load-bearing with excellent in-plane properties. Continuous fiber reinforced composites are one of the mostly used categories of advanced composites. This class of composites has gained a lot of attention due to their light-weight and decent mechanical properties. However, additional material design is required to tune both mechanical and structural properties of these composites. Since the load transfer between reinforcement phase and polymer matrix happens at the interfacial region, a better interphase might result in a composite with higher vibration damping. In this study, a gradient interphase between carbon fiber and polymer matrix has been created by using ZnO nanowires to engineer the damping loss factor of the carbon fiber composites. For the growth of ZnO nanowires on the carbon fabric, low temperature hydrothermal reaction has been used. Then the carbon fabrics with ZnO nanowires were infiltrated with a low viscosity epoxy using vacuum assisted resin transfer molding technique. The stiffness and structural damping of the composite were examined using dynamic mechanical analysis. The results show that the damping properties of hybrid composites using ZnO nanowires are enhanced compare to the bare carbon fabric composites. Since the growth of ZnO nanowires is a tunable process, the length, diameter and aspect ratio of the nanowires and consequently the architecture of the interphase can be tailored for the desired vibration damping in the system. Thus, the hybrid composites with ZnO nanowire interphase can be used to enhance the energy dissipation in a structural system.
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Zhang, Lichao, Xiujie Dou, Changjun Min, Yuquan Zhang, and Xiaocong Yuan. "In-plane trapping and manipulation of ZnO nanowires on a metallic surface." In CLEO: Applications and Technology. Washington, D.C.: OSA, 2016. http://dx.doi.org/10.1364/cleo_at.2016.jw2a.90.
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Terris, Damian, Karl Joulain, and Denis Lemonnier. "Heat Pulse Propagation in Silicon Nanostructures by Solving Phonon Transport Equation." In ASME 2008 First International Conference on Micro/Nanoscale Heat Transfer. ASMEDC, 2008. http://dx.doi.org/10.1115/mnht2008-52220.
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The temperature evolution prediction of silicon nanofilms and nanowires can be useful to safeguard high technology systems of its deterioration. The simulation of a level and a pulse in these nanostructures is then made with Boltzmann Transport Equation (BTE) resolution using the single time approximation. The Discrete Ordinate (DO) method helps to numerate the angle space. BTE is written in cylindrical coordinates which corresponds to wires. Therefore, the cylindrical plane is considered as an isotropic scattering to mimic a nanowire and then, as a specular reflexion (which conserve z momentum) to simulate a nanofilm. Using the axisymmetry done with a specular reflexion, the cylinder is two dimensionally discretized with a regular rectangular mesh.
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Fortuna, Seth A., Jianguo Wen, and Xiuling Li. "MOCVD Grown III–V Nanowires: In-Plane, self-aligned and transfer-printable." In LEOS 2008 - 21st Annual Meeting of the IEEE Lasers and Electro-Optics Society (LEOS 2008). IEEE, 2008. http://dx.doi.org/10.1109/leos.2008.4688674.
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Yin, Han, Xiaoxiang Wu, Jun Xu, Kunji Chen, and Linwei Yu. "Deterministic deployment of in-plane silicon nanowires for high performance large area electronics." In 2018 IEEE International Conference on Integrated Circuits, Technologies and Applications (ICTA). IEEE, 2018. http://dx.doi.org/10.1109/cicta.2018.8706060.
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Crouse, Michael M., Thomas L. James, and David Crouse. "Fabrication, characterization of II-VI semiconductor nanowires and applications in infrared focal plane arrays." In Optical Engineering + Applications. SPIE, 2008. http://dx.doi.org/10.1117/12.795399.
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Katsuro, Sae, Weifang Lu, Naoki Sone, Kazuma Ito, Nanami Nakayama, Renji Okuda, Yoshiya Miyamoto, et al. "Suppression of c-plane emission in GaInN/GaN multiquantum shells/nanowires for efficient LEDs." In Gallium Nitride Materials and Devices XVII, edited by Hadis Morkoç, Hiroshi Fujioka, and Ulrich T. Schwarz. SPIE, 2022. http://dx.doi.org/10.1117/12.2608186.
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Saha, Sourabh K., John J. LaColla, and Martin L. Culpepper. "An Automated Stage for Scalable Imprinting of DNA Nanowires Based on a Self-Aligning Technique." In ASME 2012 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/imece2012-87065.
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Molecular combing is an established technique for aligning DNA nanowires on a surface. When performed on micro-patterned surfaces, this technique can be used to reliably align and stretch DNA nanowires across micro pillars. Imprinting of these aligned DNA nanowires is an affordable technique for fabrication of arrays of nano-scale channels across micro-scale reservoirs. In the past, DNA combing and imprinting (DCI) have been performed manually to fabricate polymer chips that are used in biomedical applications such as gene therapy and drug delivery studies. Automation of the DCI process is necessary to improve the yield and to scale-up production for these applications. However, existing automated techniques are not appropriate for DNA nanowire imprinting because these techniques cannot handle (i) fragile stamps and (ii) individual chip scale stamps of size ∼1 cm2. Herein, we present the design, fabrication and performance evaluation of an imprinting stage that enables (i) handling fragile stamps via low-cost equipment and (ii) production scale-up via simultaneous handling of multiple stamps. The stage is based on a self-aligning imprinting technique that passively aligns a stamp parallel to the substrate thereby enabling simultaneous imprinting of multiple stamps via a single stage. This self-alignment technique minimizes nanowire breakage by ensuring (i) minimal in-plane stamp motion during imprinting and (ii) that the contact forces do not exceed the weight of the stamp. Based on this technique we have designed/fabricated a stage that can simultaneously handle three stamps and is capable of further scale-up. The stage consists of a movable platform that is mounted on linear bearings and is actuated via a stepper motor. Stamps are loaded onto a holder that is mounted on the movable platform via kinematic couplings. This allows one to rapidly attach and detach the holder from the stage and also makes it possible to handle fragile stamps during loading/unloading. Imprinting of DNA nanowires with a manual stage has demonstrated the feasibility of the self-alignment scheme. Experiments that were performed to test the alignment capability of the stage verify that conformal stamp contact can be achieved across all three stamps even in the presence of an angular misalignment of 5° between the stamp and the glass slide. This ability to simultaneously align multiple stamps is a critical step in being able to scale-up and fully automate the DCI process.
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Mavrokefalos, Anastassios, Ngoc T. Nguyen, Michael T. Pettes, David C. Johnson, and Li Shi. "In-Plane Thermal and Thermoelectric Properties of Polycrystalline Highly Preferred Orientation [(W)x(WSE2)y]z Superlattice Thin Films." In ASME/JSME 2007 Thermal Engineering Heat Transfer Summer Conference collocated with the ASME 2007 InterPACK Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/ht2007-32841.
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It was recently found by using the time domain thermal reflectance method that polycrystalline highly preferred orientation WSe2 and [(W)x(WSe2)y]z superlattice films possess extremely low cross-plane thermal conductivity, which is desirable for thermal insulation and thermoelectric energy conversion applications. However, it is difficult to obtain the in-plane thermal conductivity by using the laser reflectance or the 3-ω method. Here we employ a suspended microdevice developed for measuring thermoelectric properties of individual nanowires and nanofilms to obtain the in-plane thermal conductivity, electrical conductivity, and Seebeck coefficient of [(W)x(WSe2)y]z superlattice films. The measurement results show that the in-plane thermal conductivities of these films are much higher than the cross-plane values, making the thermal conductivity of the films highly anisotropic.
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Katsuro, Sae, Weifang Lu, Nanami Nakayama, Soma Inaba, Yukimi Jinno, Shiori Yamamura, Ayaka Shima, et al. "Establishment of process to suppress (0001)-plane emission by introducing EBL in GaInN/GaN multi-quantum shells/nanowires for efficient 480 nm-LEDs." In Gallium Nitride Materials and Devices XVIII, edited by Hadis Morkoç, Hiroshi Fujioka, and Ulrich T. Schwarz. SPIE, 2023. http://dx.doi.org/10.1117/12.2646906.
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