Anisotropic Magnetoresistance in Charge-Ordering $N{a}_{0.34}(H_{3}O{)}_{0.15}Co{O}_2$:Strong Spin-Charge Coupling and Spin Ordering

Angular-dependent in-plane magnetoresistance (AMR) for single crystal $N{a}_{0.34}(H_{3}O{)}_{0.15}Co{O}_2$ 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.