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LPEM Webinar, Friday June 19 at 2PM (Paris Time, GMT+2) by Kamran Behnia
Vendredi 19 juin à 14h00
Transport of charge and entropy in a dilute metal
Pristine strontium titanate has a large electric permittivity at low temperature and the effective Bohr radius is almost a micron long. In this context, removing a tiny fraction of oxygen atoms turns the system to a dilute metal with a sharp Fermi surface and a superconducting instability. The focus of this talk will be electronic transport in this dilute metal and their broad implications.
At low temperatures, the resistivity is quadratic in temperature, even though Umklapp scattering is absent and there is a single Fermi pocket is at the zone center. The prefactor of this T-square resistivity corresponds to what is expected in an extended version of Kadowaki-Woods scaling : In all known Fermi liquids, knowing the Fermi energy allows one to predict the rough size of the T-square prefactor. While the origin of this empirical rule, valid over 4 orders of magnitude, is not known, our recent study of quadratic thermal resistivity in other dilute metals points to an origin common with the primordial Fermi liquid, 3He.
At high temperature, the quasi-particle picture of transport in dilute metallic strontium titanate breaks up. The magnitude of resistivity implies a mean-free-path too short to be plausible. The temperature dependence of the Seebeck coefficient indicates that non-degenerate electrons are becoming heavier with warming. This new route towards mass amplification through entropy accumulation resides beyond available polaronic theories.
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