Department of Physics Papers

Document Type

Journal Article

Date of this Version

4-15-2010

Publication Source

Physical Review B

Volume

81

Start Page

134417-1

Last Page

134417-15

DOI

10.1103/PhysRevB.81.134417

Abstract

Landau theory and symmetry considerations lead us to propose an explanation for several seemingly paradoxical behaviors of charge ordering (CO) and spin ordering (SO) in the mixed valence compound LuFe2O4. Both SO and CO are highly frustrated. We analyze a lattice gas model of CO within mean-field theory and determine the magnitude of several of the phenomenological interactions. We show that the assumption of a continuous phase transitions at which CO or SO develops implies that both CO and SO are incommensurate. To explain how ferroelectric fluctuations in the charge-disordered phase can be consistent with an antiferroelectric-ordered phase, we invoke an electron-phonon interaction in which a low-energy (20 meV) zone-center transverse phonon plays a key role. The energies of all the zone center phonons are calculated from first principles. We give a Landau analysis which explains SO and we discuss a model of interactions which stabilizes the SO state, if it is assumed commensurate. However, we suggest a high-resolution experimental determination to see whether this phase is really commensurate, as believed up to now. The applicability of representation analysis is discussed. A tentative explanation for the sensitivity of the CO state to an applied magnetic field in field-cooled experiments is given.

Comments

An Erratum for this article, published at Phys. Rev. B 82, 029902 (2010), is attached as an additional file.

Additional Files

charge and spin erratum.pdf (33 kB)
Erratum

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Date Posted: 12 August 2015

This document has been peer reviewed.