Logarithmic criticality in transverse thermoelectric conductivity of the ferromagnetic topological semimetal CoMnSb

The transverse transport effect such as anomalous Hall and Nernst effect can be a good probe to indicate the topological texture in the band structure. Here, we report the results of our experimental studies on the magnetic, transport, and thermoelectric properties observed in our high-quality single crystal of the ferromagnetic metal CoMnSb. A sizable anomalous Hall conductivity σ_yx and transverse thermoelectric conductivity α_yx are found experimentally and comparable in size to the values estimated from first-principles calculation. Our experiment further reveals that CoMnSb exhibits −T log T critical behavior in α_yx(T), deviating from Fermi liquid behavior α_yx ∼ T over a decade of temperature between 10 and 400 K, similar to ferromagnetic Weyl semimetal Co₂MnGa and nodal-line semimetals Fe₃X (X = Al, Ga). Our theoretical calculation for CoMnSb also predicts the −T log T behavior when the Fermi energy locates near the Weyl nodes in momentum space.