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Thermal conductivity in the vicinity of the quantum critical endpoint in Sr3Ru2O7

F. Ronning·R. W. Hill·M. Sutherland·D. G. Hawthorn·M. A. Tanatar·J. Paglione·Louis Taillefer·M. J. Graf·R. S. Perry·Y. Maeno·A. P. Mackenzie
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Abstract

Thermal conductivity of Sr3Ru2O7 was measured down to 40 mK and at magnetic fields through the quantum critical endpoint at H_c = 7.85 T. A peak in the electrical resistivity as a function of field was mimicked by the thermal resistivity. In the limit as T -> 0 K we find that the Wiedemann-Franz law is satisfied to within 5% at all fields, implying that there is no breakdown of the electron despite the destruction of the Fermi liquid state at quantum criticality. A significant change in disorder (from $ρ_0$(H=0T) = 2.1 $μΩ$ cm to 0.5 $μΩ$ cm) does not influence our conclusions. At finite temperatures, the temperature dependence of the Lorenz number is consistent with ferromagnetic fluctuations causing the non-Fermi liquid behavior as one would expect at a metamagnetic quantum critical endpoint.

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F. Ronning, R. W. Hill, M. Sutherland, D. G. Hawthorn, M. A. Tanatar, J. Paglione, Louis Taillefer, M. J. Graf, R. S. Perry, Y. Maeno, A. P. Mackenzie. 2006-09-05. Thermal conductivity in the vicinity of the quantum critical endpoint in Sr3Ru2O7. https://doi.org/10.1103/physrevlett.97.067005

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