Ambi-polar anomalous Nernst effect in a magnetic topological insulator

Abstract

We report electromagnetic and thermomagnetic transport studies on a magnetic topological insulator thin film Cr _0.15 (Bi _0.1 Sb _0.9 ) _1.85 Te _3 grown by molecular beam epitaxy. The temperature and gate voltage dependence of the anomalous Hall effect exhibits the typical behavior of a quantum anomalous Hall insulator. The anomalous Nernst effect (ANE) shows a sign reversal when the Fermi level is tuned across the charge neutrality point of the surface Dirac cone. We show that the ambi-polar behavior of the ANE can be explained by the semiclassical Mott relation, in conjunction with the ambi-polar Dirac band structure.

Keywords

• topological insulator
• anomalous Hall effect
• anomalous Nernst effect