Anisotropic Magnetoresistance in Charge-Ordering $Na_{0.34}(H_3O)_{0.15}CoO_2$:Strong Spin-Charge Coupling and Spin Ordering

TL;DR

This study investigates the angular-dependent in-plane magnetoresistance of charge-ordered Na-based cobaltate, revealing temperature-dependent symmetry changes that indicate strong spin-charge coupling and evolving spin structures.

Contribution

It provides new insights into the spin-charge interactions and symmetry transitions in charge-ordered cobaltates through systematic AMR measurements.

Findings

AMR exhibits twofold symmetry at high temperatures

AMR transitions to sixfold symmetry below a certain temperature

Symmetry changes from twofold to fourfold at the charge-ordering temperature

Abstract

Angular-dependent in-plane magnetoresistance (AMR) for single crystal $Na_{0.34}(H_3O)_{0.15}CoO_2$ with charge ordering is studied systematically. The anisotropic magnetoresistance shows a twofold symmetry at high temperature with rotating H in the Co-O plane, while a sixfold symmetry below a certain temperature ($T_\rho$). At $T_\rho$, the symmetry of AMR changes from twofold to fourfold with rotating magnetic field (H) in the plane consisting of the current and c-axis. The variation of AMR symmetry with temperature arises from the subtle changes of the spin structure. These results give a direct evidence for the itinerant electrons directly coupled to the localized spins.