Anomalous Magnetothermopower in a Metallic Frustrated Antiferromagnet

TL;DR

This study investigates how magnetic fields influence thermopower in a frustrated antiferromagnetic metal, revealing unusual magnetothermopower behavior linked to electron-spin interactions and magnetic frustration.

Contribution

It demonstrates the significant impact of magnetic fields on thermopower in a frustrated antiferromagnet, highlighting the role of electron-spin interactions beyond magnetic ordering.

Findings

Thermopower decreases rapidly with magnetic field at T > 70 K.

Strong electron-spin interactions affect thermoelectric response.

Unusual magnetothermopower behavior linked to geometrical frustration.

Abstract

We report the temperature $T$ and magnetic field $H$ dependence of the thermopower $S$ of an itinerant triangular antiferromagnet PdCrO$_2$ in high magnetic fields up to 32 T. In the paramagnetic phase, the zero-field thermopower is positive with a value typical of good metals with a high carrier density. In marked contrast to typical metals, however, $S$ decreases rapidly with increasing magnetic field, approaching zero at the maximum field scale for $T >$ 70 K. We argue here that this profound change in the thermoelectric response derives from the strong interaction of the 4$d$ correlated electrons of the Pd ions with the short-range spin correlations of the Cr$^{3+}$ spins that persist beyond the N\'{e}el ordering temperature due to the combined effects of geometrical frustration and low dimensionality.