Phase separation instabilities and magnetism in two dimensional square and honeycomb Hubbard model

JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS

卷:383

Article; Proceedings Paper

Kocharian, A. N.¹  Fang, Kun²  Fernando, G. W.²  Balatsky, A. V.³ 

[1] Calif State Univ Los Angeles, Los Angeles, CA 90032 USA

[2] Univ Connecticut, Storrs, CT 06269 USA

[3] AlbaNova Univ Ctr Nordita, SE-10691 Stockholm, Sweden

关键词: VCA;    Mott metal-insulator transition;    Square lattice;    Honeycomb structure;    Phase separation;    Phase coexistence;    Pairing;   

DOI  :  10.1016/j.jmmm.2014.10.007

来源: Elsevier

【 摘 要 】

The variational cluster approximation is applied to rigorously calculate intrinsic local electron correlations in bipartite square and honeycomb Hubbard lattices. The Mott-Hubbard gap at half filling is manifested by a smooth metal-insulator transition in both lattices in agreement with the generic two-dimensional phase diagram. However, a density variation with the chemical potential shows the distinct structural differences away from half filling. The square lattice exhibits electron density discontinuity accompanied with spontaneous transition from antiferromagnetic Mott-Hubbard insulator into nonmagnetic metal. The spectral density anomaly and spin susceptibility peaks also are signaling on coexistence of hole rich metallic and hole poor insulating regions. In contrast, honeycomb lattice does not show density anomaly but displays a smooth transition with continuous evolution of a homogenous metallic state. These calculations provide strong evidence for spontaneous phase separation instability found in our quantum cluster calculations at moderate U Published by Elsevier B.V.

【 授权许可】

Free