Transverse thermoelectric conversion based on spin caloritronics

Abstract

The interconversion between spin, charge, and heat currents is actively studied from the viewpoints of fundamental physics and thermoelectric applications in the field of spin caloritronics. This field is a branch of spintronics, which has developed rapidly since the discovery of the thermo-spin conversion phenomenon called the spin Seebeck effect. In spin caloritronics, various thermo-spin conversion phenomena have subsequently been discovered and magneto-thermoelectric effects, thermoelectric effects unique to magnetic materials, have received renewed attention with the advances in physical understanding and thermal/thermoelectric measurement techniques. The transverse thermoelectric conversion is one of the central topics in spin caloritronics, which is usually realized by the anomalous Nernst effect (ANE) and the anomalous Ettingshausen effect (AEE) in magnetic materials. In ANE (AEE), a heat (charge) current induces a transverse charge (heat) current in the direction perpendicular to the magnetization direction. Based on this symmetry, ANE/AEE exhibits a convenient scaling law that is entirely different from that of conventional thermoelectric effects. Furthermore, the thermoelectric output of ANE/AEE can be actively controlled through the manipulation of magnetization. Thus, ANE (AEE) has the potential to realize simple and versatile thermal energy harvesting or heat-current sensing (thermal energy management) applications.In this talk, we mainly report our recent experimental progress on ANE and AEE [1-5]. We also show a novel approach for transverse thermoelectric generation that exhibits a similar symmetry to ANE but is driven by a different mechanism [6]. **