On the Thermal Conductivity of Ferromagnetics

Sato, Hisanao

doi:10.1143/ptp.13.119

Cited by 49 publications

(26 citation statements)

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“…Collision integral. The collision integral for spin bosons can be generally written as: (19) where k ′ stands for dk ′ /2π and W kk ′ is the total probability of the spin excitation to be scattered from the state k to the state k ′ . For the processes of scattering due to phonons such probabilities are given by:…”

Section: Phonon Mechanism Of Relaxationmentioning

confidence: 99%

Thermal transport in antiferromagnetic spin-chain materials

Chernyshev

Rozhkov

2005

Phys. Rev. B

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We study the problem of heat transport in one-dimensional (1D) spin-chain systems weakly coupled to three-dimensional phonons and impurities. We consider the limit of fast spin excitations and slow phonons, applicable to a number of compounds of the cuprates family, such as Sr2CuO3, where the superexchange J is much larger than the Debye energy, ΘD. In this case the Umklapp scattering among the spin excitations is strongly suppressed for all relevant temperatures. We argue that the leading scattering mechanism for the spin excitations at not too low temperatures is the "normal" (as opposed to the Umklapp) spin-phonon scattering in which the non-equilibrium momentum is transferred from the spin subsystem to phonons where it quickly relaxes through the "phonon bath". Because of the lower dimensionality of the spin excitations it is only the momentum along the chains which is conserved in such a scattering. We find that this effect leads to a particular momentum-and temperature-dependence of the spin-phonon relaxation rate valid for the broad class of low-dimensional spin systems. Subsequently we demonstrate that the spin-phonon relaxation mechanism is insufficient for the low-energy, long-wavelength 1D spin-chain excitations, which make the thermal conductivity diverge. We complete our consideration by taking into account the impurity scattering, which in 1D cuts off the quasi-ballistic spin excitations and renders the thermal conductivity finite. Altogether, these effects yield the following spin-boson thermal conductivity behavior: κs ∝ T 2 at low temperatures, κs ∝ T −1 at intermediate temperatures, and κs = const at higher temperatures T ∼ ΘD. The saturation at higher temperatures is of rather non-trivial origin and we provide a detailed discussion of it. Our results compare very well with the existing experimental data for Sr2CuO3. Using our microscopic insight into the problem we propose further experiments and predict an unusual impurity concentration dependence for a number of quantities.

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Section: Phonon Mechanism Of Relaxationmentioning

confidence: 99%

Thermal transport in antiferromagnetic spin-chain materials

Chernyshev

Rozhkov

2005

Phys. Rev. B

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“…In larger systems such as voids, filaments, and large-scale structures, the cosmic expansion plays a significant role [4,5,9]. In larger systems such as voids, filaments, and large-scale structures, the cosmic expansion plays a significant role [4,5,9].…”

Section: Discussionmentioning

confidence: 99%

“…The problem of whether a local system expands with the Universe dates back to 1933 [2] and continues to be discussed [3][4][5][6][7][8][9][10][11][12][13]. When the size of the weakly gravitating system becomes a larger fraction of H −1 0 , such as for large scale structures [4,5,9], the cosmic expansion plays a significant role in the dynamics. Contradictory answers have been given, mainly because of the use of different or unphysical coordinate systems.…”

Section: Introductionmentioning

confidence: 99%

Cosmological expansion and local systems: exact solutions

Faraoni¹

2008

Can. J. Phys.

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We study the competition between cosmological expansion and local attraction for relativistic objects embedded in a generic Friedmann universe. The recently discovered "all or nothing" behaviour (i.e., weakly coupled systems are comoving while strongly coupled ones do not expand at all) is found to be limited to the de Sitter background. New exact solutions are presented describing black holes co-moving with a surrounding universe. PACS Nos.: 98.80.−k,04.20.Jb, 04.20.−q Résumé : Nous étudions la compétition entre l'expansion cosmologique et l'attraction locale pour des objets relativistes dans un espace générique de Friedmann. Nous trouvons que le comportement récemment découvert du « tout ou rien » (les systèmes faiblement couplés évoluent de concert, alors que les systèmes fortement couplés ne subissent aucune expansion) est limité aux espaces de de Sitter. Nous présentons de nouvelles solutions exactes qui décrivent des trous noirs en évoluant de concert avec un univers les englobant.[Traduit par la Rédaction]

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“…An accurate measurement or calculation of MPC is pivotal for the correct description of the thermodynamical properties of magnetic materials [1,14,15]: The free energy will contain magnetic and vibrational contributions, often of the same magnitude. The MPC strength is maximal when spin waves (SWs) and elastic waves have the same frequency and wave number, i.e., when there is a crossing in the two dispersion curves [16].…”

Section: Introductionmentioning

confidence: 99%

Competition of lattice and spin excitations in the temperature dependence of spin-wave properties

et al. 2018

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(2018). Competition of lattice and spin excitations in the temperature dependence of spin-wave properties. Physical Review B (PRB), 97 (21). The interplay of magnons and phonons can induce strong temperature variations in the magnetic exchange interactions, leading to changes in the magnetothermal response. This is a central mechanism in many magnetic phenomena, and in the new field of Spin Caloritronics, which focuses on the combination of heat and spin currents. Boson model systems have previously been developed to describe the magnon-phonon coupling but, until recently, studies rely on empirical parameters. In this paper, we propose a first-principles approach to describe the dependence of the magnetic exchange integrals on phonon renormalization, leading to changes in the magnon dispersion as a function of temperature. The temperature enters into the spin dynamics (by introducing fluctuations) as well as in the magnetic exchange itself. Depending on the strength of the coupling, these two temperatures may or may not be equilibrated, yielding different regimes. We test our approach in typical and well-known ferromagnetic materials: Ni, Fe, and Permalloy. We compare our results to recent experiments on the spin-wave stiffness, and discuss departures from Bloch's law and parabolic dispersion. Copyright and re-use policy

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On the Thermal Conductivity of Ferromagnetics

Cited by 49 publications

References 0 publications

Thermal transport in antiferromagnetic spin-chain materials

Thermal transport in antiferromagnetic spin-chain materials

Cosmological expansion and local systems: exact solutions

Competition of lattice and spin excitations in the temperature dependence of spin-wave properties

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