Transport properties and magnetic field induced localization in the misfit cobaltite [Bi$_2$Ba$_{1.3}$K$_{0.6}$Co$_{0.1}$]$^{RS}$[CoO$_2$]$_{1.97}$ single crystal

TL;DR

This study investigates the transport properties of a misfit cobaltite single crystal, revealing magnetic field-induced localization effects and complex resistivity behaviors linked to multi-band electronic structures and possible magnetic ordering phenomena.

Contribution

It provides detailed measurements of resistivity, thermopower, and Hall effect under magnetic fields, highlighting the magnetic field-induced localization and the role of multi-band electronic structure in this material.

Findings

Magnetic field induces ln(1/T) divergence in resistivity at low temperatures.

Resistivity shows metallic behavior in-plane and semiconducting behavior out-of-plane at low T.

Positive magnetoresistance fits multi-band electronic structure models.

Abstract

Resistivity under magnetic field, thermopower and Hall coefficient are systematically studied for [Bi$_2$Ba$_{1.3}$K$_{0.6}$Co$_{0.1}$]$^{RS}$[CoO$_2$]$_{1.97}$ single crystal. In-plane resistivity ($\rho_{ab}$(T)) shows metallic behavior down to 2 K with a $T^2$ dependence below 30 K; while out-of-plane resistivity ($\rho_{c}(T)$) shows metallic behavior at high temperature and a thermal activation semiconducting behavior below about 12 K. Striking feature is that magnetic field induces a ln(1/$T$) diverging behavior in both $\rho_{ab}$ and $\rho_{c}(T)$ at low temperature. The positive magnetoresistance (MR) could be well fitted by the formula based on multi-band electronic structure. The ln(1/$T$) diverging behavior in $\rho_{ab}$ and $\rho_{c}(T)$ could arise from the magnetic-field-induced 2D weak localization or spin density wave.