The Origin of Anomalous Low-Temperature Downturns in the Thermal Conductivity of Cuprates

Abstract

We show that the anomalous decrease in the thermal conductivity of cuprates below 300 mK, as has been observed recently in several cuprate materials including Pr${}_{2-x}$Ce${}_x$CuO${}_{7-\delta }$ in the field-induced normal state, is due to the thermal decoupling of phonons and electrons in the sample. Upon lowering the temperature, the phonon-electron heat transfer rate decreases and, as a result, a heat current bottleneck develops between the phonons, which can in some cases be primarily responsible for heating the sample, and the electrons. The contribution that the electrons make to the total low-$T$ heat current is thus limited by the phonon-electron heat transfer rate, and falls rapidly with decreasing temperature, resulting in the apparent low-$T$ downturn of the thermal conductivity. We obtain the temperature and magnetic field dependence of the low-$T$ thermal conductivity in the presence of phonon-electron thermal decoupling and find good agreement with the data in both the normal and superconducting states.

8 pages, 5 figures

References in corpus (1)

• The ground state of heavily-overdoped non-superconducting La${}_{2-x}$Sr${}_x$CuO${}_4$

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• Deviation from the Wiedemann-Franz law induced by nonmagnetic impurities in overdoped La_{2-x}Sr_{x}CuO_{4}
• Doping dependence of phonon and quasiparticle heat transport of pure and Dy-doped Bi_2Sr_2CaCu_2O_{8+δ} single crystals
• Hall-Lorenz number paradox in cuprate superconductors
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