Anomalous Nernst effects in pyrochlore molybdates with spin chirality

The transverse thermoelectric (Nernst) effect on pyrochlore molybdates is investigated experimentally. In Nd 2 Mo 2 O 7 and Sm 2 Mo 2 O 7 with the spin chirality, the Nernst signal, which mostly arises from the transverse heat current (or equivalently the transverse Peltier coefficient α xy ), shows a low-temperature (20-30 K) positive extremum, whereas it is absent in (Gd 0.95 Ca 0.05 ) 2 Mo 2 O 7 with no single-spin anisotropy of the rare-earth ion and hence with no spin chirality. The correlation between the Hall conductivity σ xy and α xy in Nd 2 Mo 2 O 7 also indicates the spin chirality plays a significant role in the spontaneous (anomalous) Nernst effect.