Large Nernst effect and thermodynamics properties in Weyl antiferromagnet

The noncollinear antiferromagnet Mn₃Sn exhibits a large anomalous Hall effect (AHE) driven by a large Berry curvature despite the vanishingly small magnetization. Theoretically, the large Berry curvature in antiferromagnets is predicted to be induced by the time-reversal breaking Weyl state in momentum space. Here, we comprehensively study the thermal conductivity, specific heat, thermoelectric power S(T), and thermomagnetic power S_ji(T) in single crystals of Mn₃Sn. Mn₃Sn exhibited a large spontaneous anomalous Nernst effect (ANE) at room temperature; in particular, the signal magnitude of Mn₃Sn exceeded 0.6 μV/K, which is comparable to that of ordinary ferromagnets. The large ANE results from the magnetic Weyl states near the Fermi level E_F and likely shares its origin with the AHE. Moreover, the possibility of Nernst-type thermoelectric modules was evaluated by analyzing the basic thermal and electric physical properties. (author)