Articles de revues : « Spin wave instability »

1

Nazarov, A. V., R. G. Cox et C. E. Patton. « General spin wave instability theory ». IEEE Transactions on Magnetics 37, n^o 4 (juillet 2001) : 2380–82. http://dx.doi.org/10.1109/20.951178.

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2

Okabe, Takuya. « Spin-wave instability in itinerant ferromagnets ». Physical Review B 57, n^o 1 (1 janvier 1998) : 403–11. http://dx.doi.org/10.1103/physrevb.57.403.

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3

Scalapino, D. J., E. Loh et J. E. Hirsch. « d-wave pairing near a spin-density-wave instability ». Physical Review B 34, n^o 11 (1 décembre 1986) : 8190–92. http://dx.doi.org/10.1103/physrevb.34.8190.

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4

Haghshenasfard, Z., H. T. Nguyen et M. G. Cottam. « Spin-wave Instability Theory for Ferromagnetic Nanostructures ». Acta Physica Polonica A 127, n^o 2 (février 2015) : 192–97. http://dx.doi.org/10.12693/aphyspola.127.192.

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5

ANDERSSON, NILS, et KOSTAS D. KOKKOTAS. « THE R-MODE INSTABILITY IN ROTATING NEUTRON STARS ». International Journal of Modern Physics D 10, n^o 04 (août 2001) : 381–441. http://dx.doi.org/10.1142/s0218271801001062.

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In this review we summarize the current understanding of the gravitational-wave driven instability associated with the so-called r-modes in rotating neutron stars. We discuss the nature of the r-modes, the detailed mechanics of the instability and its potential astrophysical significance. In particular we discuss results regarding the spin-evolution of nascent neutron stars, the detectability of r-mode gravitational waves and mechanisms limiting the spin-rate of accreting neutron stars in binary systems.

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MALOZOVSKY, Y. M., et J. D. FAN. « SUPERCONDUCTIVITY FROM SPIN-WAVE EXCITATIONS NEAR THE FERROMAGNETIC AND ANTIFERROMAGNETIC INSTABILITIES ». International Journal of Modern Physics B 19, n^o 01n03 (30 janvier 2005) : 77–85. http://dx.doi.org/10.1142/s0217979205027974.

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We study pairing by the exchange of spin-wave excitations near the ferromagnetic or antiferromagnetic instability in terms of the effective two-particles T-matrix. We show that near the ferromagnetic instability the paring due to the exchange of the paramagnetic excitations can occur in the p-wave state (ℓ=1) and m=±1. We show that near the antiferromagnetic instability the pairing due to the exchange by the paramagnetic excitations occurs also in the p-wave state (ℓ=1) but with m=0 and that there is no pairing in d-wave state.

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7

EPSHTEIN, ERNEST, YURI GULYAEV et PETER ZILBERMAN. « JOINT ACTION OF SPIN-TRANSFER AND SPIN-INJECTION TORQUES IN FERROMAGNETIC JUNCTIONS ». International Journal of Nanoscience 06, n^o 05 (octobre 2007) : 363–66. http://dx.doi.org/10.1142/s0219581x0700495x.

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We consider theoretically a current flowing perpendicular to interfaces of a spin-valve type ferromagnetic metallic junction. For the first time a simultaneous action of the two current effects is investigated, namely, the nonequilibrium longitudinal spin injection and the transverse spin surface torque. Dispersion relations for fluctuations are derived and solved under the proper boundary conditions. Joint action of the two effects mentioned lowers the instability threshold, its typical value being 1 × 106–3 × 107 A/cm2. Spin wave excitations may soften near the threshold. A nonlinear problem is solved about steady state arising due to instability development.

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8

KASIMOV, ASLAN R., et D. SCOTT STEWART. « Spinning instability of gaseous detonations ». Journal of Fluid Mechanics 466 (10 septembre 2002) : 179–203. http://dx.doi.org/10.1017/s0022112002001192.

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We investigate hydrodynamic instability of a steady planar detonation wave propagating in a circular tube to three-dimensional linear perturbations, using the normal mode approach. Spinning instability is identified and its relevance to the well-known spin detonation is discussed. The neutral stability curves in the plane of heat release and activation energy exhibit bifurcations from low-frequency to high-frequency spinning modes as the heat release is increased at fixed activation energy. With a simple Arrhenius model for the heat release rate, a remarkable qualitative agreement with experiment is obtained with respect to the effects of dilution, initial pressure and tube diameter on the behaviour of spin detonation. The analysis contributes to the explanation of spin detonation which has essentially been absent since the discovery of the phenomenon over seventy years ago.

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9

Brey, L., et B. I. Halperin. « Spin-density-wave instability in wide parabolic quantum wells ». Physical Review B 40, n^o 17 (15 décembre 1989) : 11634–38. http://dx.doi.org/10.1103/physrevb.40.11634.

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10

Machida, Kazushige, et Masaru Kato. « Inherent Spin-Density-Wave Instability in Heavy-Fermion Superconductivity ». Physical Review Letters 58, n^o 19 (11 mai 1987) : 1986–88. http://dx.doi.org/10.1103/physrevlett.58.1986.

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Zhang, Y. T., C. E. Patton, G. Srinivasan, G. O. White, C. J. Brower et C. A. Edmondson. « Measurement of the spin‐wave instability thresholdhcritin microwave ferrites ». Review of Scientific Instruments 58, n^o 4 (avril 1987) : 620–23. http://dx.doi.org/10.1063/1.1139226.

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12

MINO, M. « Control of spin-wave instability threshold in YIG sphere ». Physica B : Condensed Matter 329-333 (mai 2003) : 1227–28. http://dx.doi.org/10.1016/s0921-4526(02)02162-2.

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13

Araújo, W., F. M. de Aguiar, A. Azevedo et S. M. Rezende. « Spin wave instability in simultaneous orthogonal and parallel pumping ». Journal of Magnetism and Magnetic Materials 272-276 (mai 2004) : 1003–4. http://dx.doi.org/10.1016/j.jmmm.2003.12.055.

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14

Kato, Masaru, et Kazushige Machida. « Inherent Spin Density Wave Instability in Heavy-Fermion Superconductors ». Journal of the Physical Society of Japan 56, n^o 6 (15 juin 1987) : 2136–48. http://dx.doi.org/10.1143/jpsj.56.2136.

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15

BARCI, DANIEL G., et PAULO S. A. BONFIM. « SUPERCONDUCTIVITY NEAR POMERANCHUK INSTABILITIES IN THE SPIN CHANNEL ». Modern Physics Letters B 27, n^o 14 (16 mai 2013) : 1350102. http://dx.doi.org/10.1142/s0217984913501029.

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We study the competition between a Pomeranchuk instability in the spin channel with angular momentum ℓ = 1 and an attractive interaction, favoring Cooper-pair formation. We found that the superconducting gap strongly suppresses the phase space for the Pomeranchuk instability. We computed a mean-field phase diagram displaying a first order transition between two superconductor phases with different symmetries: p-wave (with spontaneously generated spin-orbit interaction) and s-wave for greater values of the coupling constant. Moreover, we have looked for a possible modulated superconducting phase. We have found that this phase appears only as a metastable state in the strong coupling regime.

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16

Malozovsky, Y. M., et J. D. Fan. « Pseudogap and Unconventional Pairing in the Hubbard Model ». International Journal of Modern Physics B 12, n^o 29n31 (20 décembre 1998) : 2939–45. http://dx.doi.org/10.1142/s0217979298001812.

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The attractive (U < 0) and repulsive (U > 0) Hubbard models have been studied using the Fermi liquid perturbation approach. The attractive Hubbard model (U < 0) is an adequate model for 3 He , an incompressible and strongly paramagnetic liquid [Formula: see text], [Formula: see text] for |U|N F = 0.9) with a pseudogap in the charge response. A pairing instability and superfluidity for U < 0 exists in the spin channel only: spin-triplet with l = 0, or spin-singlet with l = 1 (p-wave orbital state j = s + l = 1), where l is the orbital momentum of a pair. The repulsive Hubbard model (U > 0) represents a highly compressible and nearly antiferromagnetic liquid [Formula: see text], [Formula: see text] for UN F = 0.9) with a pseudogap in the spin response. However, for U > 0 a pairing instability and superconductivity exist in the charge channel only: spin-singlet with l = 0 (s-wave), or with l = 2 (d-wave) in the case of an anisotropic Fermi surface.

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17

Gerus, Sergei, et Edwin Lock. « Experimental methods for the study of spin waves ». Izvestiya VUZ. Applied Nonlinear Dynamics 30, n^o 5 (30 septembre 2022) : 520–33. http://dx.doi.org/10.18500/0869-6632-003002.

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Purpose of this paper is to give an overview of various experimental methods for investigation of spin waves characteristics. Methods. The paper presents a description of a number of experimental techniques, such as the probing method, the phase shift method, the method of measure of equiphase dependences, the method of intersecting wave beams, and the use of Fourier analysis of the complex transfer coefficient of spin waves to determine their spatial spectrum. The conditions for using the listed methods and the characteristics of spin waves that one can measure by means of these methods are discussed in detail. Results. The paper presents a number of fundamental results that have been obtained on the basis of described methods. For example, the probing method was successfully used to visualize the amplitude and phase distribution of spin waves in the ferrite film plane and, in particular, it was used to experimentally confirm the previously predicted appearance of super-directed propagation of surface and backward volume spin wave beams. The phase-shift measurement method made it possible to measure the dispersion dependence of spin waves in ferrite structures such as ferrite – metal and ferrite – dielectric – metal, where measurements cannot be made by the probing method. The method of measuring equiphase dependences of spin waves made it possible, in particular, to measure for the first time with great accuracy the value of an external magnetic field magnetizing an yttrium iron garnet film to saturation in various crystallographic directions. The method of intersecting wave beams has made it possible to clarify the mechanism of parametric instability of surface spin waves. Fourier analysis of the complex transfer coefficient of spin waves allowed to determine the spatial spectrum of these waves; in particular, dispersion dependences of higher modes of the backward volume spin wave were first measured using this method. Conclusion. The methods described in this paper may continue to be successfully used for investigations of spin waves characteristics in various magnon crystals, ferrite structures and meta-structures.

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18

IOFFE, L. B., et A. I. LARKIN. « EFFECTIVE ACTION OF A TWO-DIMENSIONAL ANTIFERROMAGNET ». International Journal of Modern Physics B 02, n^o 02 (avril 1988) : 203–19. http://dx.doi.org/10.1142/s0217979288000160.

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In the limit of weak quantum fluctuations an effective long-wave action of the Heisenberg quantum antiferromagnet is obtained which allows one to get a spectrum, spin, and statistics of long-wave fluctuations. In the vicinity of the point of instability of an antiferromagnetic state quantum fluctuations result (at zero temperature as well) in a paramagnetic phase of a spin liquid.

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19

Pecora, Louis M. « Derivation and generalization of the Suhl spin-wave instability relations ». Physical Review B 37, n^o 10 (1 avril 1988) : 5473–77. http://dx.doi.org/10.1103/physrevb.37.5473.

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20

Kostylev, M. P., B. A. Kalinikos et H. Dötsch. « Parallel pump spin wave instability threshold in thin ferromagnetic films ». Journal of Magnetism and Magnetic Materials 145, n^o 1-2 (mars 1995) : 93–110. http://dx.doi.org/10.1016/0304-8853(94)01612-7.

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21

Iqbal, Z., U. Khanum et G. Murtaza. « Lower hybrid wave instability in a spin-polarized degenerate plasma ». Contributions to Plasma Physics 59, n^o 3 (16 octobre 2018) : 284–91. http://dx.doi.org/10.1002/ctpp.201800075.

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22

Rosa, P. F. S., J. Kang, Yongkang Luo, N. Wakeham, E. D. Bauer, F. Ronning, Z. Fisk, R. M. Fernandes et J. D. Thompson. « Competing magnetic orders in the superconducting state of heavy-fermion CeRhIn5 ». Proceedings of the National Academy of Sciences 114, n^o 21 (9 mai 2017) : 5384–88. http://dx.doi.org/10.1073/pnas.1703016114.

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Applied pressure drives the heavy-fermion antiferromagnet CeRhIn5 toward a quantum critical point that becomes hidden by a dome of unconventional superconductivity. Magnetic fields suppress this superconducting dome, unveiling the quantum phase transition of local character. Here, we show that 5% magnetic substitution at the Ce site in CeRhIn5, either by Nd or Gd, induces a zero-field magnetic instability inside the superconducting state. This magnetic state not only should have a different ordering vector than the high-field local-moment magnetic state, but it also competes with the latter, suggesting that a spin-density-wave phase is stabilized in zero field by Nd and Gd impurities, similarly to the case of Ce0.95Nd0.05CoIn5. Supported by model calculations, we attribute this spin-density wave instability to a magnetic-impurity-driven condensation of the spin excitons that form inside the unconventional superconducting state.

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23

O’Brien, Enda. « Balancing the Potential Vorticity Seesaw : The Bare Essentials of Baroclinic Instability ». Earth Systems and Environment 3, n^o 3 (18 octobre 2019) : 341–51. http://dx.doi.org/10.1007/s41748-019-00128-7.

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Abstract This paper bypasses the mathematical technicalities of baroclinic instability and tries to provide a more conceptual, mechanistic explanation for a phenomenon that is fundamentally important to the dynamics of the earth’s atmosphere and oceans. The standard conceptual picture of baroclinic instability is reviewed and stripped down to identify the most essential features. These are: (a) Regions with both positive and negative potential vorticity (PV) gradients, (b) separate Rossby wave perturbations in each region where PV gradients are of different signs, and (c) cooperative phase locking between Rossby waves in regions of opposite PV gradient, which renders them stationary, and allows them to amplify to reduce the background temperature gradient (or baroclinicity) while still conserving total PV. These three factors constitute the “counterpropagating Rossby wave” perspective, and suggest the heuristic picture of a “PV seesaw”, which remains balanced as the instabilities (i.e., the phase-locked PV wave perturbations) grow out along opposite limbs. After reviewing the key characteristics of PV and Rossby waves, the process is illustrated by the spontaneous onset of baroclinic instability during spin-up of the Held–Suarez dynamical core atmospheric model.

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Patton, C. E., G. Srinivasan, W. Jantz, W. Wettling, W. D. Wilber et J. G. Booth. « Preludes to spin‐wave chaos : Spin‐wave instability processes, butterfly curves, kinks, flips, cusps, and shifts (invited) (abstract) ». Journal of Applied Physics 64, n^o 10 (15 novembre 1988) : 5401. http://dx.doi.org/10.1063/1.342382.

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Drozdovskii, A. V., B. A. Kalinikos, A. B. Ustinov et A. Stashkevich. « Spin-wave self-modulation instability in a perpendicularly magnetized magnonic crystal ». Journal of Physics : Conference Series 769 (novembre 2016) : 012071. http://dx.doi.org/10.1088/1742-6596/769/1/012071.

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26

Meersschaut, J., J. Dekoster, R. Schad, P. Beliën et M. Rots. « Spin Density Wave Instability for Chromium in Fe/Cr(100) Multilayers ». Physical Review Letters 75, n^o 8 (21 août 1995) : 1638–41. http://dx.doi.org/10.1103/physrevlett.75.1638.

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27

Rezende, S. M., O. F. de Alcantara Bonfim et F. M. de Aguiar. « Model for chaotic dynamics of the perpendicular-pumping spin-wave instability ». Physical Review B 33, n^o 7 (1 avril 1986) : 5153–56. http://dx.doi.org/10.1103/physrevb.33.5153.

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Belczynski, K., et S. Banerjee. « Formation of low-spinning 100 M⊙ black holes ». Astronomy & ; Astrophysics 640 (août 2020) : L20. http://dx.doi.org/10.1051/0004-6361/202038427.

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Aims. It is speculated that a merger of two massive stellar-origin black holes in a dense stellar environment may lead to the formation of a massive black hole in the pair-instability mass gap (∼50−135 M⊙). Such a merger-formed black hole is expected to typically have a high spin (a ∼ 0.7). If such a massive black hole acquires another black hole it may lead to another merger detectable by LIGO/Virgo in gravitational waves. Acquiring a companion may be hindered by gravitational-wave kick/recoil, which accompanies the first merger and may quickly remove the massive black hole from its parent globular or nuclear cluster. We test whether it is possible for a massive merger-formed black hole in the pair-instability gap to be retained in its parent cluster and have low spin. Such a black hole would be indistinguishable from a primordial black hole. Methods. We employed results from numerical relativity calculations of black hole mergers to explore the range of gravitational-wave recoil velocities for various combinations of merging black hole masses and spins. We compared merger-formed massive black hole speeds with typical escape velocities from globular and nuclear clusters. Results. We show that a globular cluster is highly unlikely to form and retain a ∼100 M⊙ black hole if the spin of the black hole is low (a ≲ 0.3). Massive merger-formed black holes with low spins acquire high recoil speeds (≳ 200 km s−1) from gravitational-wave kick during formation that exceed typical escape speeds from globular clusters (∼ 50 km s−1). However, a very low-spinning (a ∼ 0.1) and massive (∼100 M⊙) black hole could be formed and retained in a galactic nuclear star cluster. Even though such massive merger-formed black holes with such low spins acquire high speeds during formation (∼ 400 km s−1), they may avoid ejection since massive nuclear clusters have high escape velocities (∼ 300−500 km s−1). A future detection of a massive black hole in the pair-instability mass gap with low spin would therefore not be proof of the existence of primordial black holes, which are sometimes claimed to have low spins and arbitrarily high masses.

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Chen, C. I., M. C. Lin et C. K. Chen. « Surface Instabilities on a Thin Power-Law Fluid During Spin Coating ». Journal of Mechanics 30, n^o 5 (22 mai 2014) : 505–13. http://dx.doi.org/10.1017/jmech.2014.39.

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AbstractThe phenomena of surface instabilities in a thin power-law fluid during spin coating are investigated. The set of Navier-Stokes equations with non-Newtonian behavior in the region of low Reynolds number serves as a mathematical description of the physical systems. Long-wave perturbation analysis is proposed to derive an evolution equation of the Ostwald de-Waele type fluid to govern the propagation of surface waves. Weakly nonlinear dynamics of film flow is studied by the multiple scales method. The amplitude of instability is determined by a Ginzburg-Landau equation. The study reveals that the degree of power-law index plays a vital role in stabilizing the film flow. The shear-thinning fluid is more unstable than the shear-thickening fluid in the stability analysis. Further, the nonlinear wave speed in the supercritical stability region decreases with increasing values of power-law index.

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Smith, Joseph C., Seth T. Rittenhouse, Ryan M. Wilson et Brandon M. Peden. « Bogoliubov theory of a Bose–Einstein condensate of rigid rotor molecules ». Journal of Physics B : Atomic, Molecular and Optical Physics 54, n^o 20 (20 octobre 2021) : 205302. http://dx.doi.org/10.1088/1361-6455/ac34dd.

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Abstract We consider a BEC of rigid rotor molecules confined to quasi-2D through harmonic trapping. The molecules are subjected to an external electric field which polarizes the gas, and the molecules interact via dipole–dipole interactions. We present a description of the ground state and low-energy excitations of the system including an analysis of the mean-field energy, polarization, and stability. Under large electric fields the gas becomes fully polarized and we reproduce a well known density-wave instability which arises in polar BECs. Under smaller applied electric fields the gas develops an in-plane polarization leading to the emergence of a new global instability as the molecules ‘tilt’. The character of these instabilities is clarified by means of momentum-space density–density structure factors. A peak at zero momentum in the spin–spin structure factor for the in-plane component of the polarization indicates that the tilt instability is a global phonon-like instability.

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31

METZNER, W. « RENORMALISATION GROUP ANALYSIS OF THE TWO-DIMENSIONAL HUBBARD MODEL : SPIN CORRELATIONS AND D-WAVE SUPERCONDUCTIVITY ». International Journal of Modern Physics B 17, n^o 28 (10 novembre 2003) : 5279–88. http://dx.doi.org/10.1142/s0217979203020417.

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The repulsive two-dimensional Hubbard model is analysed within a functional renormalisation group (RG) approach. The flow equation for the effective interactions is evaluated on 1-loop level. The effective interactions diverge at a finite energy scale which is exponentially small for small bare interactions. To analyse the nature of the instabilities signalled by the diverging interactions, we compute the flow of the superconducting susceptibilities for various pairing symmetries and also charge and spin density susceptibilities. Depending on the choice of the model parameters (hopping amplitudes, interaction strength and band-filling) we find spin density wave instabilities or d-wave superconductivity as leading instability close to half-filling. This calculation establishes the existence of d-wave superconductivity in the Hubbard model beyond doubt.

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Iqbal, Z., Imran A. Khan et G. Murtaza. « On the upper hybrid wave instability in a spin polarized degenerate plasma ». Physics of Plasmas 25, n^o 6 (juin 2018) : 062121. http://dx.doi.org/10.1063/1.5022143.

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33

Zhang, Y. T., C. E. Patton et G. Srinivasan. « Spin‐wave instability and ‘‘true’’ foldover in single‐crystal YIG films (abstract) ». Journal of Applied Physics 63, n^o 8 (15 avril 1988) : 4160. http://dx.doi.org/10.1063/1.340527.

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Chen, M., C. E. Patton, G. Srinivasan et Y. T. Zhang. « Ferromagnetic resonance foldover and spin-wave instability in single-crystal YIG films ». IEEE Transactions on Magnetics 25, n^o 5 (1989) : 3485–87. http://dx.doi.org/10.1109/20.42343.

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Slavin, A. N., G. Srinivasan, S. S. Cordone et V. B. Cherepanov. « Instability mechanism of collective spin wave oscillations in finite‐size ferrite samples ». Journal of Applied Physics 75, n^o 10 (15 mai 1994) : 5610–12. http://dx.doi.org/10.1063/1.355657.

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36

BenAli, A., et R. Bennaceur. « Spin density wave instability induced by a magnetic field in quasi-two-dimensional d-wave superconductors ». Physica C : Superconductivity 460-462 (septembre 2007) : 778–80. http://dx.doi.org/10.1016/j.physc.2007.04.013.

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37

WRÓBEL, P., et L. JACAK. « SPIN PEIERLS INSTABILITY AGAINST S-LIKE ANISOTROPIC SUPERCONDUCTIVITY IN FRAMEWORK OF THE MEAN FIELD RVB-HUBBARD MODEL ». Modern Physics Letters B 02, n^o 01 (mars 1988) : 511–16. http://dx.doi.org/10.1142/s0217984988000096.

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It is shown theoretically that the superconducting transition in the framework of RVB mean field treatment in nearly half-filled band Hubbard model is substantially influenced by spin density wave instability. The reasonable SDW and SC ordering phase diagram for doped La 2 CuO 4 compounds is found.

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NISAMANEEPHONG, P. « LINEAR RESPONSE THEORY FOR DISORDERED BOSONS ». International Journal of Modern Physics B 14, n^o 19n20 (10 août 2000) : 2135–55. http://dx.doi.org/10.1142/s0217979200001266.

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Within the hard-core boson model and the 1/S spin wave approximation, we have constructed the linear response theory for disordered boson system. Our numerical results shows that the instability of the superfluidity occurs when the paramagnetic part cancels out the diamagnetic part with a critical finite amout of disorder.

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Tsai, S. W., et J. B. Marston. « κ(BEDTTTF)2X organic crystals : Superconducting versus anti-ferromagnetic instabilities in the Hubbard model on an anisotropic triangular lattice ». Canadian Journal of Physics 79, n^o 11-12 (1 décembre 2001) : 1463–67. http://dx.doi.org/10.1139/p01-085.

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A Hubbard model at half-filling on an anisotropic triangular lattice has been proposed as the minimal model to describe conducting layers of κ(BEDTTTF)2X organic materials. The model interpolates between the square lattice and decoupled chains. The κ(BEDTTTF)2X materials have many similarities with cuprates, such as the presence of unconventional metallic properties and the close proximity of superconducting and anti-ferromagnetic phases. As in cuprates, spin fluctuations are expected to play a crucial role in the onset of superconductivity. We perform a weak-coupling renormalization-group analysis to show that a superconducting instability occurs. Frustration in the anti-ferromagnetic couplings, which arises from the underlying geometrical arrangement of the lattice, breaks the perfect nesting of the square lattice at half-filling. The spin-wave instability is suppressed and a superconducting instability predominates. For the isotropic triangular lattice, there are again signs of long-range magnetic order, in agreement with studies at strong-coupling. PACS Nos.: 74.30G, 76.50

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40

Cox, Richard G., Carl E. Patton, Michael A. Wittenauer, Pavel Kabos et Liang Chen. « Spin wave instability in single crystal Zn–Y hexagonal ferrite at 8.93 GHz ». Journal of Applied Physics 89, n^o 8 (15 avril 2001) : 4454–69. http://dx.doi.org/10.1063/1.1352689.

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An, Sung Yong, Pavol Krivosik, Michael A. Kraemer, Heidi M. Olson, Alexey V. Nazarov et Carl E. Patton. « High power ferromagnetic resonance and spin wave instability processes in Permalloy thin films ». Journal of Applied Physics 96, n^o 3 (août 2004) : 1572–80. http://dx.doi.org/10.1063/1.1763996.

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Drozdovskii, A. V., et B. A. Kalinikos. « Observation of self-modulation spin-wave instability in a one-dimensional magnonic crystal ». JETP Letters 95, n^o 7 (juin 2012) : 357–61. http://dx.doi.org/10.1134/s0021364012070041.

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Eremin, I., M. Eremin, S. Varlamov, D. Brinkmann, M. Mali et J. Roos. « Spin susceptibility and pseudogap inYBa2Cu4O8:An approach via a charge-density-wave instability ». Physical Review B 56, n^o 17 (1 novembre 1997) : 11305–11. http://dx.doi.org/10.1103/physrevb.56.11305.

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Lin, M. C., et C. K. Chen. « Finite amplitude long-wave instability of a thin viscoelastic fluid during spin coating ». Applied Mathematical Modelling 36, n^o 6 (juin 2012) : 2536–49. http://dx.doi.org/10.1016/j.apm.2011.09.009.

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Jia, Hui-Xian, et Dong-Ming Shan. « Nonlinear Stage of Modulation Instability for a Fifth-Order Nonlinear Schrödinger Equation ». Zeitschrift für Naturforschung A 72, n^o 11 (26 octobre 2017) : 1071–75. http://dx.doi.org/10.1515/zna-2017-0227.

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AbstractIn this article, a fifth-order nonlinear Schrödinger equation, which can be used to characterise the solitons in the optical fibre and inhomogeneous Heisenberg ferromagnetic spin system, has been investigated. Akhmediev breather, Kuzentsov soliton, and generalised soliton have all been attained via the Darbox transformation. Propagation and interaction for three-type breathers have been studied: the types of breather are determined by the module and complex angle of parameter ξ; interaction between Akhmediev breather and generalised soliton displays a phase shift, whereas the others do not. Modulation instability of the generalised solitons have been analysed: a small perturbation can develop into a rogue wave, which is consistent with the results of rogue wave solutions.

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Grigoryevskaya, Angelica A., et Pavel Yu Gulyaev. « Spin instability of technological combustion mode in a wave of self-propagating high-temperature synthesis ». Yugra State University Bulletin 18, n^o 1 (10 mai 2022) : 9–20. http://dx.doi.org/10.18822/byusu2022019-20.

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The results of a computer experiment to determine the invariant properties of the Trace transform of a two-dimensional chronogram of wave propagation in the spin combustion mode of the Ni-Al system are presented. The chronogram model was chosen in the form of four sets of isocline lines, the angle of inclination of which corresponded to the value of the tangential velocity from 16.5 to 41.8 m/s. A high degree of shift invariance of the Trace-transformation nodes was found, the error in determining the coordinates of which is limited only by the presence of the initial additive geometric noise in the image of the differential chronogram of the combustion wave. Scale invariance properties in practice provide a dynamic magnification range of 40 dB.

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Acharya, Swagata, Dimitar Pashov, Elena Chachkarova, Mark van Schilfgaarde et Cédric Weber. « Electronic Structure Correspondence of Singlet-Triplet Scale Separation in Strained Sr2RuO4 ». Applied Sciences 11, n^o 2 (6 janvier 2021) : 508. http://dx.doi.org/10.3390/app11020508.

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At a temperature of roughly 1 K, Sr2RuO4 undergoes a transition from a normal Fermi liquid to a superconducting phase. Even while the former is relatively simple and well understood, the superconducting state has not even been understood after 25 years of study. More recently, it has been found that critical temperatures can be enhanced by the application of uniaxial strain, up to a critical strain, after which it falls off. In this work, we take an “instability” approach and seek divergences in susceptibilities. This provides an unbiased way to distinguish tendencies to competing ground states. We show that in the unstrained compound, the singlet and triplet instabilities of the normal Fermi liquid phase are closely spaced. Under uniaxial strain, electrons residing on all orbitals contributing to the Fermiology become more coherent, while the electrons of the Ru-dxy character become heavier, and the electrons of the Ru-dxz,yz characters become lighter. In the process, Im χ(q,ω) increases rapidly around q=(0.3,0.3,0)2π/a and q=(0.5,0.25,0)2π/a, while it gets suppressed at all other commensurate vectors, in particular at q=0, which is essential for spin-triplet superconductivity. We observe that the magnetic anisotropy under strain drops smoothly, which is concomitant with the increment in singlet instability. Thus, the triplet superconducting instability remains the lagging instability of the system, and the singlet instability enhances under strain, leading to a large energy-scale separation between these competing instabilities. However, since this happens even without spin-orbit coupling, we believe it is primarily the enhancement in the spin fluctuation glue around quasi-anti-ferromagnetic vectors that drives the Cooper pairing instead of the magnetic anisotropy. At large strain, an instability to a spin density wave overtakes the superconducting one. The analysis relies on a high-fidelity, ab initio description of the one-particle properties and two-particle susceptibilities, based on the quasiparticle self-consistent GWapproximation augmented by dynamical mean field theory. This approach is described and its high fidelity confirmed by comparing to observed one- and two-particle properties.

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Pouresmaeeli, F., S. H. Abedinpour et B. Tanatar. « Density and pseudo-spin rotons in a bilayer of soft-core bosons ». Journal of Physics B : Atomic, Molecular and Optical Physics 56, n^o 12 (26 mai 2023) : 125001. http://dx.doi.org/10.1088/1361-6455/acd599.

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Abstract We study the dynamics of a bilayer system of bosons with repulsive soft-core Rydberg-dressed interactions within the mean-field Bogoliubov-de Gennes approximation. We find roton minima in both symmetric and asymmetric collective density modes of the symmetric bilayer. Depending on the density of bosons in each layer and the spacing between two layers, the homogeneous superfluid phase becomes unstable in either (or both) of these two channels, leading to density and pseudo-spin-density wave instabilities in the system. Breaking the symmetry between two layers, either with a finite counterflow or a density imbalance renormalizes the dispersion of collective modes and makes the system more susceptible to density-wave instability.

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Jiang, Hong-Min, Zi-Jian Yao et Fu-Chun Zhang. « Fermi surface nesting and spin density wave instability in the overdoped superconducting iron pnictides ». EPL (Europhysics Letters) 100, n^o 4 (1 novembre 2012) : 47004. http://dx.doi.org/10.1209/0295-5075/100/47004.

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Nazarov, A. V., C. E. Patton, R. G. Cox, L. Chen et P. Kabos. « General spin wave instability theory for anisotropic ferromagnetic insulators at high microwave power levels ». Journal of Magnetism and Magnetic Materials 248, n^o 2 (juillet 2002) : 164–80. http://dx.doi.org/10.1016/s0304-8853(02)00171-3.

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