Extended Kohler's scaling, a low temperature anomaly and Isosbestic point in the charge density wave state of 1T-VSe$_2$

TL;DR

This study investigates the charge density wave state of 1T-VSe2, revealing an extended Kohler's rule, a low-temperature MR anomaly, and an isosbestic point in thermoelectric properties, contributing new insights into its electronic transport behavior.

Contribution

It introduces the observation of an extended Kohler's rule, a low-temperature MR anomaly, and an isosbestic point in 1T-VSe2's CDW state, highlighting novel transport phenomena.

Findings

Kohler's rule holds above T_CDW, extended below T_CDW

An anomaly in MR and thermal excitation carrier density at 20 K

Presence of an isosbestic point in Seebeck coefficient curves

Abstract

1T-VSe$_2$ is a narrow band transition metal chalcogenide that shows charge density wave (CDW) state below $T_{CDW}$ = 110 K. Here, we have explored the relevance of Kohler's rule and the thermal transport properties of VSe$_2$ across the CDW state. The magnetoresistance (MR) follows Kohler's rule above $T_{CDW}$, while an extended Kohler's rule is employed below $T_{CDW}$. Interestingly, we observed an anomaly in MR at T = 20 K, below which MR value decreases on lowering temperature. This anomaly is also reflected in the slope ($\kappa$) of Kohler's plots and the relative change in the thermal excitation induced carrier density ($n_T$) also. The $T_{CDW}$ remains largely unaffected in both electrical resistivity ($\rho(T)$) and longitudinal Seebeck coefficient ($\it{S_{xx}}$) even under a strong magnetic field of 14 Tesla. However, the application of magnetic field enhances the peak intensity of $\it{S_{xx}}$ at T $\sim$ 60 K. Additionally, $\it{S_{xx}(T)}$ curves measured at different fields exhibit a crossover at T = 20 K, which suggest the existence of unique feature in the CDW state of VSe$_2$ \textit{i.e.} a locally exact isosbestic point.