Field-Induced Fermi Surface Reconstruction in Na_(0.5)CoO_(2)

摘要

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 corresponding to only 1 percent of the area of the orthorhombic Brillouin zone (BZ) were clearly observed, suggesting that most of the original Fermi surface vanished at the charge ordering (CO) transition. In-plane magnetic fields were found to suppress strongly the CO state. For fields rotated within the conducting planes, we observe angular magnetoresistance oscillations whose periodicity changes from two-to six-fold at the transition. This suggests the field-induced reconstruction of the Fermi surface upon suppression of the CO-state