Fig. 2: Large, spontaneous topological Nernst effect (TNE) and topological Hall effect (THE) in the compensated antiferromagnet CoNb3S6.
a Experimental setup (schematic) for measurement of TNE. The magnetic field and temperature gradient are B∥c and − ∇ T∥a, respectively. b Isotherms of the total Nernst effect Sxy(B) before subtraction of the linear part related to the classical Lorentz force on moving charge carriers, and topological Nernst effect \({S}_{xy}^{{{{\rm{T}}}}}(B)\) after subtraction (left axis). The right axis shows the magnetization M at T = 26 K, just below the Néel temperature TN. Dashed horizontal line: Expected saturation magnetization of Co2+ ions. Inset: expanded view of M in the low-B regime, with hysteresis. c, d Magnetic field dependence of thermoelectric and electric coefficients around TN, with offset shifts. At T = 30 K and above, Sxy and ρyx are linear in B, reflecting the normal Hall and Nernst effects induced by B. e, f T-dependence of THE \({\rho }_{yx}^{{{{\rm{T}}}}}\) and TNE \({S}_{xy}^{{{{\rm{T}}}}}\) in B = 0, where red (blue) symbols correspond to field-cooling in positive (negative) B. Insets: experimental measurement geometries. g, h Temperature dependence of topological Nernst and Hall conductivities \({\alpha }_{xy}^{{{{\rm{T}}}}}\) and \({\sigma }_{xy}^{{{{\rm{T}}}}}\). The solid lines indicate ab-initio calculated values for Fermi energy EF = 15 meV, while the symbols show experimental data obtained in B = 0 after field cooling (FC). See Supplementary Fig. 8 for detailed EF dependence. i Magnetization dependence of zero-field (spontaneous) thermoelectric Nernst effects Sxy for CoNb3S6 and related magnetic materials.
