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Holes as Dipoles in a Doped Antiferromagnet and Stripe Instabilities

By Su-Peng Kou and Zheng-Yu Weng

Abstract

Based on an effective model of a doped antiferromagnetic Mott insulator, we show that a doped hole will induce a dipole-like spin configuration in a spin ordered phase at low doping. The kinetic energy of doped holes is severely frustrated and a hole-dipole object is actually localized or self-trapped in space. Without a balance from the kinetic energy, the long-range dipole-dipole interaction between doped holes will dominate the low-energy physics, leading to an inhomogeneity instability as hole-dipoles collapse into stripes. Both antiphase metallic stripes of quarter-filling and antiphase insulating stripes along a diagonal direction are discussed as composed of hole-dipoles as elementary building blocks. Stripe melting and competing phases are also discussed.Comment: 11 pages, 5 figures, revised version with reference updates, to appear in Phys. Rev.

Topics: Condensed Matter - Strongly Correlated Electrons
Publisher: 'American Physical Society (APS)'
Year: 2003
DOI identifier: 10.1103/PhysRevB.67.115103
OAI identifier: oai:arXiv.org:cond-mat/0212134

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