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Magnetic-field-induced Fermi surface reconstruction in Na$_{0.5}$CoO$_2$

L. Balicas·M. Abdel-Jawad·N. E. Hussey·F. C. Chou·P. A. Lee
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Abstract

We have performed electrical transport measurements at low temperatures and high magnetic fields in Na$_{0.5}$CoO$_2$ single crystals. Shubnikov de Haas oscillations were observed for two frequencies F_1 150 and F_2 40 T corresponding respectively to 1 and .25% of the area of the orthorhombic Brillouin zone. These small Fermi surface (FS) pockets indicate that most of the original FS vanishes at the charge ordering (CO) transition. Furthermore, in-plane magnetic fields strongly suppress the CO state. For fields rotating within the conducting planes we observe angular magnetoresistance oscillations (AMRO), whose periodicity changes from two- to six-fold at the transition, suggesting that a reconstructed hexagonal FS emerges at a field of about 40 T.

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L. Balicas, M. Abdel-Jawad, N. E. Hussey, F. C. Chou, P. A. Lee. 2004-10-15. Magnetic-field-induced Fermi surface reconstruction in Na$_{0.5}$CoO$_2$. https://arxiv.org/abs/cond-mat/0410400

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