Large field-induced anomalous Hall effect in itinerant frustrated antiferromagnet PdCrO₂

PdCrO₂ is one of the rare metallic triangular-lattice antiferromagnets in the ultraclean limit. We report the observation of unusually large anomalous Hall (AH) effect in PdCrO₂ induced by high magnetic field near T_N. The field-induced AH conductivity (σ_xy^A), measured in a high-quality micro-structured single crystal, is found to be exceptionally large as compared to magnetization (M), yielding the maximum AH factor S_H = σ_xy^A/M, two orders of magnitude larger than found in ferromagnets. Such an enhancement of S_H is observed in the intermediate temperature regime near T_N, but is suppressed either well below or above T_N. These findings demonstrate that scattering of highly mobile electrons of short-range spin correlation among the frustrated spins can be an effective source on large AH effect.