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In-plane ferromagnetism in charge-ordering $Na_{0.55}CoO_2$

C. H. Wang·X. H. Chen·T. Wu·X. G. Luo·G. Y. Wang·J. L. Luo
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Abstract

The magnetic and transport properties are systematically studied on the single crystal $Na_{0.55}CoO_2$ with charge ordering and divergency in resistivity below 50 K. A long-range ferromagnetic ordering is observed in susceptibility below 20 K with the magnetic field parallel to Co-O plane, while a negligible behavior is observed with the field perpendicular to the Co-O plane. It definitely gives a direct evidence for the existence of in-plane ferromagnetism below 20 K. The observed magnetoresistance (MR) of 30 % at the field of 6 T at low temperatures indicates an unexpectedly strong spin-charge coupling in triangle lattice systems.

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C. H. Wang, X. H. Chen, T. Wu, X. G. Luo, G. Y. Wang, J. L. Luo. 2005-12-20. In-plane ferromagnetism in charge-ordering $Na_{0.55}CoO_2$. https://doi.org/10.1103/physrevlett.96.216401

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