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Title: Magnetodielectric Effect in the S = 1/2 Quasi-Two-Dimensional Antiferromagnet K 2V 3O 8

Abstract

We report the optical and magneto-optical properties of K{sub 2}V{sub 3}O{sub 8}, an S = 1/2 quasi-two-dimensional Heisenberg antiferromagnet. Local spin density approximation electronic structure calculations are used to assign the observed excitations and analyze the field-dependent features. Two large magneto-optical effects, centered at {approx}1.19 and 2.5 eV, are attributed to field-induced changes in the V{sup 4+} d {yields} d on-site excitations due to modification of the local crystal field environment of the VO{sub 5} square pyramids with applied magnetic field. Taken together, the evidence for a soft lattice, the presence of vibrational fine structure on the sharp 1.19 eV magneto-optical feature, and the fact that these optical excitations are due to transitions from a nearly pure spin-polarized V d state to hybridized states involving both V and O, suggest that the magneto-dielectric effect in K{sub 2}V{sub 3}O{sub 8} is driven by strong lattice coupling.

Authors:
 [1];  [1];  [1];  [2];  [3];  [2];  [2];  [2];  [2]
  1. University of Tennessee, Knoxville (UTK)
  2. ORNL
  3. Florida State University
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1003266
DOE Contract Number:
DE-AC05-00OR22725
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review B; Journal Volume: 73; Journal Issue: 7
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; APPROXIMATIONS; CRYSTAL FIELD; D STATES; ELECTRONIC STRUCTURE; FINE STRUCTURE; MAGNETIC FIELDS; MAGNETO-OPTICAL EFFECTS; MODIFICATIONS; SPIN

Citation Formats

Rai, R. C., Cao, J., Musfeldt, J. L., Singh, David J, Wei, X., Jin, Rongying, Zhou, Zhixian, Sales, Brian C, and Mandrus, David. Magnetodielectric Effect in the S = 1/2 Quasi-Two-Dimensional Antiferromagnet K2V3O8. United States: N. p., 2006. Web. doi:10.1103/PhysRevB.73.075112.
Rai, R. C., Cao, J., Musfeldt, J. L., Singh, David J, Wei, X., Jin, Rongying, Zhou, Zhixian, Sales, Brian C, & Mandrus, David. Magnetodielectric Effect in the S = 1/2 Quasi-Two-Dimensional Antiferromagnet K2V3O8. United States. doi:10.1103/PhysRevB.73.075112.
Rai, R. C., Cao, J., Musfeldt, J. L., Singh, David J, Wei, X., Jin, Rongying, Zhou, Zhixian, Sales, Brian C, and Mandrus, David. Sun . "Magnetodielectric Effect in the S = 1/2 Quasi-Two-Dimensional Antiferromagnet K2V3O8". United States. doi:10.1103/PhysRevB.73.075112.
@article{osti_1003266,
title = {Magnetodielectric Effect in the S = 1/2 Quasi-Two-Dimensional Antiferromagnet K2V3O8},
author = {Rai, R. C. and Cao, J. and Musfeldt, J. L. and Singh, David J and Wei, X. and Jin, Rongying and Zhou, Zhixian and Sales, Brian C and Mandrus, David},
abstractNote = {We report the optical and magneto-optical properties of K{sub 2}V{sub 3}O{sub 8}, an S = 1/2 quasi-two-dimensional Heisenberg antiferromagnet. Local spin density approximation electronic structure calculations are used to assign the observed excitations and analyze the field-dependent features. Two large magneto-optical effects, centered at {approx}1.19 and 2.5 eV, are attributed to field-induced changes in the V{sup 4+} d {yields} d on-site excitations due to modification of the local crystal field environment of the VO{sub 5} square pyramids with applied magnetic field. Taken together, the evidence for a soft lattice, the presence of vibrational fine structure on the sharp 1.19 eV magneto-optical feature, and the fact that these optical excitations are due to transitions from a nearly pure spin-polarized V d state to hybridized states involving both V and O, suggest that the magneto-dielectric effect in K{sub 2}V{sub 3}O{sub 8} is driven by strong lattice coupling.},
doi = {10.1103/PhysRevB.73.075112},
journal = {Physical Review B},
number = 7,
volume = 73,
place = {United States},
year = {Sun Jan 01 00:00:00 EST 2006},
month = {Sun Jan 01 00:00:00 EST 2006}
}
  • We have explored the magnetic excitation spectrum of the S=1/2 square lattice Heisenberg antiferromagnet, K{sub 2}V{sub 3}O{sub 8}, using both triple-axis and time-of-flight inelastic neutron scattering. The long-wavelength spin waves are consistent with the previously determined Hamiltonian for this material. A small energy gap of 72{+-}9 {micro}eV is observed at the antiferromagnetic zone center and the near-neighbor exchange constant is determined to be 1.08{+-}0.03 meV. A finite ferromagnetic interplanar coupling is observed along the crystallographic c axis with a magnitude of J{sub c}=-0.0036{+-}0.0006 meV. However, upon approaching the zone boundary, the observed excitation spectrum deviates significantly from the expectation ofmore » linear spin wave theory resulting in split modes at the ({pi}/2,{pi}/2) zone boundary point. The effects of magnon-phonon interaction, orbital degrees of freedom, multimagnon scattering, and dilution/site randomness are considered in the context of the mode splitting. Unfortunately, no fully satisfactory explanation of this phenomenon is found and further theoretical and experimental work is needed.« less
  • Here, BaCo 2V 2O 8 consists of Co chains in which a Co 2+ ion carries a fictitious spin 1/2 with Ising anisotropy. We performed elastic and inelastic neutron scattering experiments in BaCo 2V 2O 8 in a magnetic field perpendicular to the c axis which is the chain direction. With applying magnetic field along the a axis at 3.5 K, the antiferromagnetic order with the easy axis along the c axis, observed in zero magnetic field, is completely suppressed at 8 T, while the magnetic field gradually induces an antiferromagnetic order with the spin component along the b axis.more » We also studied magnetic excitations as a function of transverse magnetic field. The lower boundary of the spinon excitations splits gradually with increasing magnetic field. The overall feature of the magnetic excitation spectra in the magnetic field is reproduced by the theoretical calculation based on the spin 1/2 XXZ antiferromagnetic chain model, which predicts that the dynamic magnetic structure factor of the spin component along the chain direction is enhanced and that along the field direction has clear incommensurate correlations.« less
    Cited by 1
  • We study the application of a magnetic field transverse to the easy axis, Ising direction in the quasi-two-dimensional kagome staircase magnet, Co 3V 2O 8, induces three quantum phase transitions at low temperatures, ultimately producing a novel high field polarized state, with two distinct sublattices. New time-of-flight neutron scattering techniques, accompanied by large angular access, high magnetic field infrastructure allow the mapping of a sequence of ferromagnetic and incommensurate phases and their accompanying spin excitations. Also, at least one of the transitions to incommensurate phases at μ 0H c1~6.25 T and μ 0H c2~7 T is discontinuous, while the finalmore » quantum critical point at μ 0H c3~13 T is continuous.« less
  • No abstract prepared.