Zero- and finite-temperature mean field study of magnetic field induced electric polarization in Ba 2CoGe 2O 7: Effect of the antiferroelectric coupling

Judit Romhányi, Miklós Lajkó, K. Penc

Research output: Contribution to journalArticle

20 Citations (Scopus)

Abstract

We investigate the spin induced polarization in the multiferroic compound Ba 2CoGe 2O 7 using variational and finite-temperature mean field approaches, with the aim to reproduce the peculiar behavior of the induced polarization in a magnetic field observed experimentally in Murakawa. The compound is usually described by a spin-3/2 Heisenberg model extended with easy-plane anisotropy and Dzyaloshinskii-Moriya (DM) interaction. By applying a magnetic field parallel to the [110] axis, three phases can be distinguished in this model: (i) At high magnetic field, we find a partially magnetized phase with spins parallel to the fields and uniform polarization. (ii) Below a critical field, the ground state is a twofold-degenerate canted antiferromagnet, where the degeneracy can be lifted by a finite DM interaction. (iii) At zero field, a U(1) symmetry-breaking phase takes place, exhibiting a Goldstone mode. We find that extending the Hamiltonian with an antiferroelectric term results in the appearance of a canted ferrimagnetic phase for h 1 T. This phase is characterized by a finite staggered polarization, as well as by a magnetization closing a finite angle with the applied field leading to torque anomalies.

Original languageEnglish
Article number224419
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume84
Issue number22
DOIs
Publication statusPublished - Dec 20 2011

Fingerprint

Polarization
Magnetic fields
polarization
magnetic fields
Hamiltonians
Temperature
temperature
closing
Ground state
torque
Magnetization
broken symmetry
Anisotropy
Torque
interactions
anomalies
magnetization
anisotropy
ground state

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Electronic, Optical and Magnetic Materials

Cite this

@article{fbf62e78d4204883afcedc9ad3765fec,
title = "Zero- and finite-temperature mean field study of magnetic field induced electric polarization in Ba 2CoGe 2O 7: Effect of the antiferroelectric coupling",
abstract = "We investigate the spin induced polarization in the multiferroic compound Ba 2CoGe 2O 7 using variational and finite-temperature mean field approaches, with the aim to reproduce the peculiar behavior of the induced polarization in a magnetic field observed experimentally in Murakawa. The compound is usually described by a spin-3/2 Heisenberg model extended with easy-plane anisotropy and Dzyaloshinskii-Moriya (DM) interaction. By applying a magnetic field parallel to the [110] axis, three phases can be distinguished in this model: (i) At high magnetic field, we find a partially magnetized phase with spins parallel to the fields and uniform polarization. (ii) Below a critical field, the ground state is a twofold-degenerate canted antiferromagnet, where the degeneracy can be lifted by a finite DM interaction. (iii) At zero field, a U(1) symmetry-breaking phase takes place, exhibiting a Goldstone mode. We find that extending the Hamiltonian with an antiferroelectric term results in the appearance of a canted ferrimagnetic phase for h 1 T. This phase is characterized by a finite staggered polarization, as well as by a magnetization closing a finite angle with the applied field leading to torque anomalies.",
author = "Judit Romh{\'a}nyi and Mikl{\'o}s Lajk{\'o} and K. Penc",
year = "2011",
month = "12",
day = "20",
doi = "10.1103/PhysRevB.84.224419",
language = "English",
volume = "84",
journal = "Physical Review B-Condensed Matter",
issn = "0163-1829",
publisher = "American Physical Society",
number = "22",

}

TY - JOUR

T1 - Zero- and finite-temperature mean field study of magnetic field induced electric polarization in Ba 2CoGe 2O 7

T2 - Effect of the antiferroelectric coupling

AU - Romhányi, Judit

AU - Lajkó, Miklós

AU - Penc, K.

PY - 2011/12/20

Y1 - 2011/12/20

N2 - We investigate the spin induced polarization in the multiferroic compound Ba 2CoGe 2O 7 using variational and finite-temperature mean field approaches, with the aim to reproduce the peculiar behavior of the induced polarization in a magnetic field observed experimentally in Murakawa. The compound is usually described by a spin-3/2 Heisenberg model extended with easy-plane anisotropy and Dzyaloshinskii-Moriya (DM) interaction. By applying a magnetic field parallel to the [110] axis, three phases can be distinguished in this model: (i) At high magnetic field, we find a partially magnetized phase with spins parallel to the fields and uniform polarization. (ii) Below a critical field, the ground state is a twofold-degenerate canted antiferromagnet, where the degeneracy can be lifted by a finite DM interaction. (iii) At zero field, a U(1) symmetry-breaking phase takes place, exhibiting a Goldstone mode. We find that extending the Hamiltonian with an antiferroelectric term results in the appearance of a canted ferrimagnetic phase for h 1 T. This phase is characterized by a finite staggered polarization, as well as by a magnetization closing a finite angle with the applied field leading to torque anomalies.

AB - We investigate the spin induced polarization in the multiferroic compound Ba 2CoGe 2O 7 using variational and finite-temperature mean field approaches, with the aim to reproduce the peculiar behavior of the induced polarization in a magnetic field observed experimentally in Murakawa. The compound is usually described by a spin-3/2 Heisenberg model extended with easy-plane anisotropy and Dzyaloshinskii-Moriya (DM) interaction. By applying a magnetic field parallel to the [110] axis, three phases can be distinguished in this model: (i) At high magnetic field, we find a partially magnetized phase with spins parallel to the fields and uniform polarization. (ii) Below a critical field, the ground state is a twofold-degenerate canted antiferromagnet, where the degeneracy can be lifted by a finite DM interaction. (iii) At zero field, a U(1) symmetry-breaking phase takes place, exhibiting a Goldstone mode. We find that extending the Hamiltonian with an antiferroelectric term results in the appearance of a canted ferrimagnetic phase for h 1 T. This phase is characterized by a finite staggered polarization, as well as by a magnetization closing a finite angle with the applied field leading to torque anomalies.

UR - http://www.scopus.com/inward/record.url?scp=84855306766&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=84855306766&partnerID=8YFLogxK

U2 - 10.1103/PhysRevB.84.224419

DO - 10.1103/PhysRevB.84.224419

M3 - Article

AN - SCOPUS:84855306766

VL - 84

JO - Physical Review B-Condensed Matter

JF - Physical Review B-Condensed Matter

SN - 0163-1829

IS - 22

M1 - 224419

ER -