Magnetic critical behavior and anomalous Hall effect in 2H-Co$_{0.22}$TaS$_{2}$ single crystals

TL;DR

This study reveals ferromagnetism, critical magnetic behavior, and anomalous Hall effect in 2H-Co$_{0.22}$TaS$_{2}$ single crystals, highlighting long-range spin interactions and extrinsic mechanisms behind the Hall effect.

Contribution

It provides the first detailed analysis of magnetic critical behavior and the origin of the anomalous Hall effect in 2H-Co$_{0.22}$TaS$_{2}$, demonstrating long-range interactions and extrinsic AHE mechanisms.

Findings

Critical exponents follow Widom scaling, indicating 3D Heisenberg type interactions.

Exchange interaction decays as approximately r^{-4.69}.

AHE is dominated by extrinsic side-jump mechanism.

Abstract

We report ferromagnetism in 2H-Co$_{0.22}$TaS$_2$ single crystals where Co atoms are intercalated in the van der Waals gap, and a systematic study of its magnetic critical behavior in the vicinity of $T_c \sim 28$ K. The obtained critical exponents $\beta$ = 0.43(2), $\gamma$ = 1.15(1), and $\delta = 3.54(1)$ fulfill the Widom scaling relation $\delta = 1+\gamma/\beta$ and follow the scaling equation. This indicates that the spin coupling in 2H-Co$_{0.22}$TaS$_2$ is of three-dimensional Hersenberg type coupled with long-range magnetic interaction, and that the exchange interaction decays with distance as $J(r)\approx r^{-4.69}$. 2H-Co$_{0.22}$TaS$_2$ exhibits a weak temperature-dependent metallic behavior in resistivity and negative values of thermopower with dominant electron-type carriers, in which obvious anomalies were observed below $T_c$ as well as the anomalous Hall effect (AHE). The linear scaling behavior between the modified anomalous Hall resistivity $\rho_{xy}/\mu_0H$ and longitudinal resistivity $\rho_{xx}^2M/\mu_0H$ implies that the origin of AHE in 2H-Co$_{0.22}$TaS$_2$ should be dominated by the extrinsic side-jump mechanism.