Electrical and thermal transport in van der Waals magnets 2H-M_{x}TaS_{2} (M=Mn, Co)

Abstract

We report a detailed study of electrical and thermal transport properties in 2H-M_{x}TaS_{2} (M=Mn, Co) magnets where M atoms are intercalated in the van der Waals gap. The intercalation induces ferromagnetism (FM) with an easy-plane anisotropy in 2H-Mn_{x}TaS_{2}, but FM with a strong uniaxial anisotropy in 2H-Co_{0.22}TaS_{2}, which finally evolves into a three-dimensional antiferromagnetism (AFM) in 2H-Co_{0.34}TaS_{2}. Temperature-dependent electrical resistivity shows metallic behavior for all samples. Thermopower is negative in the whole temperature range for 2H-Co_{x}TaS_{2}, whereas the sign changes from negative to positive with increasing Mn for 2H-Mn_{x}TaS_{2}. The diffusive thermoelectric response dominates in both high- and low-temperature ranges for all samples. A clear kink in electrical resistivity, a weak anomaly in thermal conductivity, as well as a slope change in thermopower were observed at the magnetic transitions for 2H-Mn_{0.28}TaS_{2} (T_{c}≈ 82 K) and 2H-Co_{0.34}TaS_{2} (T_{N}≈ 36 K), respectively, albeit weaker for lower x crystals. Co-intercalation promoted FM to AFM transition is further confirmed by Hall resistivity; the sign change of the ordinary Hall coefficient indicates a multiband behavior in 2H-Co_{x}TaS_{2}.