Coexistence of Large Nernst Effect and Axis‐Dependent Conduction Polarity in Semimetal MoSi 2

ABSTRACT Transverse thermoelectric phenomena are often considered as an alternative strategy for improving thermoelectric performance beyond standard longitudinal Seebeck response. Here, we show that the semimetallic compound is a rare example of a material in which transverse thermopower arises from two different mechanisms. In zero magnetic field, this response may originate from axis‐dependent conduction polarity (ADCP), which is confirmed in by the observation of Seebeck coefficients of opposite signs along two crystallographic directions, in agreement with theoretical predictions. The presence of ADCP is further reflected in Hall effect measurements performed along the same crystallographic directions. In applied magnetic field, a second mechanism becomes operative. The combination of nearly perfect charge carrier compensation, high carrier mobility and possibly phonon‐drag effect generates a pronounced Nernst thermopower and Nernst power factor ( and at K and T). As these characteristics are not unique to , our results expand the range of materials in which large Nernst effect and ADCP may coexist, providing new opportunities to optimize transverse thermoelectric performance.