Doped bilayer antiferromagnets: Hole dynamics on both sides of a magnetic ordering transition
Abstract
The two-layer square lattice quantum antiferromagnet with spins 1/2 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 t-J Hamiltonian. To model the spin background we propose a ground-state wave function for the undoped system which 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 of 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 (pi/2,pi/2). For large interplane coupling the hole dispersion is similar to that of a free fermion (with reduced bandwidth). The cross-over between these two scenarios occurs inside the antiferromagnetic phase which indicates that the hole dynamics is governed by the local environment of the hole.
Keywords
Cite
@article{arxiv.cond-mat/9901326,
title = {Doped bilayer antiferromagnets: Hole dynamics on both sides of a magnetic ordering transition},
author = {Matthias Vojta and Klaus W. Becker},
journal= {arXiv preprint arXiv:cond-mat/9901326},
year = {2009}
}
Comments
14 pages, 11 figs, minor changes, discussion of spin correlations added, accepted for publication in PRB