Doped bilayer antiferromagnets: hole dynamics on both sides of a magnetic ordering transition

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Contributors

Abstract

The two-layer square lattice quantum antiferromagnet with spins (Formula presented) shows a magnetic order-disorder transition at a critical ratio of the interplane to intraplane couplings. We investigate the dynamics of a single hole in a bilayer antiferromagnet described by a (Formula presented) Hamiltonian. To model the spin background we propose a ground-state wave function for the undoped system that covers both magnetic phases and includes transverse as well as longitudinal spin fluctuations. The photoemission spectrum is calculated using the spin-polaron picture for the whole range of the ratio of the magnetic couplings. This allows for the study of the hole dynamics on both sides of the magnetic order-disorder transition. For small interplane coupling we find a quasiparticle with properties known from the single-layer antiferromagnet, e.g., the dispersion minimum is at (Formula presented) For large interplane coupling the hole dispersion is similar to that of a free fermion (with reduced bandwidth). The crossover between these two scenarios occurs inside the antiferromagnetic phase, which indicates that the hole dynamics is governed by the local environment of the hole.

Details

Original languageEnglish
Pages (from-to)15201-15213
Number of pages13
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume60
Issue number22
Publication statusPublished - 1999
Peer-reviewedYes