Anomalous Magnetothermopower in a Metallic Frustrated Antiferromagnet

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 Néel ordering temperature due to the combined effects of geometrical frustration and low dimensionality.

5 pages and 4 figures in Main text + 4 pages and 5 figures in Supplementary material

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• Unconventional aspects of electronic transport in delafossite oxides
• From basic properties to the Mott design of correlated delafossites
• Hidden Mott insulator in metallic PdCrO${}_2$
• Unconventional magnetism and electronic state in frustrated layered system PdCrO${}_2$
• Magnetic frustration and spontaneous rotational symmetry breaking in PdCrO2
• Investigation of Planckian behavior in a high-conductivity oxide: PdCrO${}_2$
• Probing spin correlations using angle resolved photoemission in a coupled metallic/Mott insulator system
• Heisenberg spins on an anisotropic triangular lattice: PdCrO2 under uniaxial stress
• Adsorbate-induced formation of a surface-polarity-driven nonperiodic superstructure