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arXiv · 1006.3949

Thermal drag revisited: Boltzmann versus Kubo

Suhas Gangadharaiah·A. L. Chernyshev·Wolfram Brenig
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Abstract

The effect of mutual drag between phonons and spin excitations on the thermal conductivity of a quantum spin system is discussed. We derive general expression for the drag component of the thermal current using both Boltzmann equation approach and Kubo linear-response formalism to leading order in the spin-phonon coupling. We demonstrate that aside from higher-order corrections which appear in the Kubo formalism both approaches yield identical results for the drag thermal conductivity. We discuss the range of applicability of our result and provide a generalization of our consideration to the cases of fermionic excitations and to anomalous forms of boson-phonon coupling. Several asymptotic regimes of our findings relevant to realistic situations are highlighted.

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Suhas Gangadharaiah, A. L. Chernyshev, Wolfram Brenig. 2010-10-14. Thermal drag revisited: Boltzmann versus Kubo. https://doi.org/10.1103/physrevb.82.134421

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