Disproportionation, metal-insulator transition, and critical interaction strength in Na1/2CoO2 -: art. no. 026403

被引：49

作者：

Lee, KW ^{[1
]}

Kunes, J

Novak, P

Pickett, WE

机构：

[1] Univ Calif Davis, Dept Phys, Davis, CA 95616 USA

[2] Acad Sci Czech Republ, Inst Phys, CZ-16253 Prague 6, Czech Republic

来源：

PHYSICAL REVIEW LETTERS | 2005年 / 94卷 / 02期

关键词：

D O I：

10.1103/PhysRevLett.94.026403

中图分类号：

O4 [物理学];

学科分类号：

0702 ;

摘要：

Charge disproportionation (CD) and spin differentiation in Na1/2CoO2 are studied using the correlated band local-density approximation + Hubbard U (LDA+U) approach. The simultaneous CD and gap opening seen previously is followed in detail through a first-order charge disproportionation transition 2Co(3.5+)-->Co3++Co4+. Disproportionation in the Co a(g) orbital results in half of the ions (Co3+) becoming electronically and magnetically dead, transforming the quarter-filled a(g) system into a half-filled subsystem that subsequently undergoes the observed charge ordering or metal-insulator transition. Comparing with data in the xapproximate to0.3 regime suggests the system has moved into the multiband regime where the effective Coulomb repulsion U-->U-eff=U/root3 strongly lessens correlation effects.

引用

页数：4

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