First-principles study on thermoelectric properties of half-Heusler compounds CoMSb (M = Sc, Ti, V, Cr, and Mn)

Abstract

We have performed systematic density functional calculations and evaluated thermoelectric properties, Seebeck coefficient and anomalous Nernst coefficient of half-Heusler comounds CoMSb(M=Sc, Ti, V, Cr, and Mn). The carrier concentration dependence of Seebeck coefficients in nonmagnetic compounds are in good agreement with experimental values. We found that the half-metallic ferromagnetic CoMnSb show large anomalous Nernst effect originating from Berry curvature at the Brillouin zone boundary. These results help to understanding for the mechanism of large anomalous Nernst coefficient and give us a clue to design high performance magnetic thermoelectric materials.

Crystal Structure and Magnetic Properties of the Ferromagnet CoMnSb

“…Wyckoff [23] and by the first-principles calculation [15]. The previous experimental [17,22] and theoretical [20] studies of CoMnSb-SL support the 4 B /f.u.…”

“…can be attributed to two differences in the crystal structure. First, the distance between nearest neighboring Co atoms is 2.89 Å in CoMnSb-SL and 4.15 Å in CoMnSb-HH, which may cause the larger positive Co magnetic moment of +0.55 B in CoMnSb-SL relative to the -0.3 B in CoMnSb-HH [15], as predicted by the first-principles calculation [20]. Second, there are three Mn and two Sb sites in CoMnSb-SL, while each element has only one site in CoMnSb-HH.…”

“…Experimental search for ferromagnetic systems featuring the large Berry curvature around F is a promising route to realize large ANE [12,13]. Minami et al theoretically predicted large ANE in half-Heusler intermetallic ferromagnet CoMSb (M = V, Cr, and Mn) [14,15]. According to their simulation, the ANE is over 4.5 μV/K in CoVSb, 3 μV/K in CoCrSb, and 1.2 μV/K in CoMnSb.…”

First-principles study of anomalous Nernst effect in half-metallic iron dichloride monolayer

“…Here, we neglected these effects and assumed the constant relaxation time based on our previous study on a half-metallic material. 36 We have previously used this method successfully to study the thermoelectric properties of half-Heusler compounds and skyrmion crystals. 3,10,36…”

Topological current for transverse electrical and thermal conductivity in thermoelectric effect

“…It is well known the transverse conductivities are expressed as a function of Berry curvature. In anomalous transport case at low temperatures, we thus have [17,18] Ç Ç , they satisfy the consistency condition t ab t bc t ca =1. The object that one constructed by putting together this collection of Cartesian products is called a complex linear bundle L. The manifold X is called the base.…”