Anomalous Nernst effects in pyrochlore molybdates with spin chirality

Abstract

The transverse thermoelectric (Nernst) effect on pyrochlore molybdates is investigated experimentally. In Nd2Mo2O7 and Sm2Mo2O7 with the spin chirality, the Nernst signal, which mostly arises from the transverse heat current (or equivalently the transverse Peltier coefficient αxy), shows a low-temperature (20-30 K) positive extremum, whereas it is absent in (Gd0.95Ca0.05)2Mo2O7 with no single-spin anisotropy of the rare-earth ion and hence with no spin chirality. The correlation between the Hall conductivity σxy and αxy in Nd2Mo2O7 also indicates the spin chirality plays a significant role in the spontaneous (anomalous) Nernst effect. © 2008 The American Physical Society.