Zero‐Field Nernst Effect in a Ferromagnetic Kagome‐Lattice Weyl‐Semimetal Co₃Sn₂S₂

Abstract

The discovery of magnetic topological semimetals has recently attracted significant attention in the field of topology and thermoelectrics. In a thermoelectric device based on the Nernst geometry, an external magnet is required as an integral part. Reported is a zero‐field Nernst effect in a newly discovered hard‐ferromagnetic kagome‐lattice Weyl‐semimetal Co3Sn2S2. A maximum Nernst thermopower of ≈3 µV K−1 at 80 K in zero field is achieved in this magnetic Weyl‐semimetal. The results demonstrate the possibility of application of topological hard magnetic semimetals for low‐power thermoelectric devices based on the Nernst effect and are thus valuable for the comprehensive understanding of transport properties in this class of materials.

Record thermopower found in an IrMn-based spintronic stack

“…Anomalous Nernst effect as a function of IrMn thickness. In addition to the Seebeck effect, the anomalous Nernst effect (ANE) [68][69][70][71][72][73] is also investigated with different IrMn thicknesses with magnetic fields applied out of the plane of the film and ANE voltages measured along a line normal to the in-plane temperature gradient. The Nernst coefficients at room temperature are extracted for all samples (see Supplementary Note 15 and Supplementary Fig.…”

Largely Suppressed Magneto-Thermal Conductivity and Enhanced Magneto-Thermoelectric Properties in PtSn 4

“…When a conductive solid is placed under a longitudinal temperature gradient and a transverse magnetic field, two types of thermoelectric responses occur, i.e., the magneto-Seebeck effect in the longitudinal direction and the Nernst effect in the other transverse direction [9]. Both longitudinal and transverse thermoelectric effects have recently received attention in the studies of topological semimetals, specifically, studies of giant magnetic-field enhancement of the thermoelectric properties [10,11] or exploration of the Berry curvature-related anomalous thermoelectric transport phenomena [12][13][14][15][16][17][18]. For instance, in the Dirac semimetal Cd 3 As 2 [19], which has ultrahigh carrier mobility [20], anomalous magneto-Seebeck and Nernst effects were recently observed [12,14], and the relationship between these anomalous transport properties with Berry curvature was discussed.…”

Spin‐Dependent Thermoelectric Transport in Cobalt‐Based Heusler Alloys

“…There were not only comparisons of multiple experimental methods, but also the discovery of new physics and ANE of large magnitudes. [20,[25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43] The improved basic understanding of ANE has made it possible to continuously find materials, including the recently discovered Weyl magnets, with large anomalous Nernst coefficients. For example, due to the important contribution of the Berry phase to the transport properties, a large ANE was measured in antiferromagnet Mn 3 Sn, [43] in which the net magnetization is vanishingly small.…”

“…In magnetic materials, there is also an anomalous Nernst effect (ANE), which can be considered as the thermoelectric counterpart of the anomalous Hall effect (AHE); the transverse electric field is a consequence of the magnetization of the material with a longitudinal temperature gradient, rather than due to an externally applied magnetic field. Until now, ANE has been well investigated in many different materials, including the conventional ferromagnetic materials, [25][26][27][28][29][30][31] oxides Fe 3 O 4 [32] and SrRuO 3 crystals, [33] half-metallic ferromagnet (FM) La 2∕3 Sr 1∕3 MnO 3 thin films, [34] rare-earth alloys, [35] multilayered [Pt/Co] n , [36] spin valves, [37] ferromagnetic semiconductors, [38] Weyl/Dirac semimetals, [39][40][41] and antiferromagnetic materials. [20,42,43] The ANE as a phenomenon was well known long before the era of condensed matter physics; however, it is still not fully understood.…”