Origin of negative anomalous Nernst thermopower in Mn-Ga ordered alloys

The negative sign of the anomalous Nernst thermopower (SANE) observed in Mn-Ga ordered alloys is an attractive property for thermoelectric applications exploiting effect (ANE); however, its origin has not been clarified. In this study, to gain insight into SANE, we prepared epitaxial thin films MnxGa100−x with x ranging from 56.2 71.7 and systematically investigated structural, magnetic, transport properties, including Hall (AHE) ANE. measured SANE all samples shows close one order magnitude difference among different compositions. Together were able separate two contributions ANE, i.e., originating transverse coefficient (αxy) other AHE acting on longitudinal carrier flow induced by Seebeck effect. Both are found be samples, while experimentally obtained αxy exhibits a monotonic increase toward zero increasing x, which consistent tendency indicated first-principle calculations. Our results show that large mostly attributed αxy, thus shed light further enhancement ANE Mn-based alloys.