Dzyaloshinskii-Moriya interaction inNaV2O5:A microscopic study

Abstract

We present a unified account of magnetic exchange and Raman scattering in the quasi-one-dimensional transitionmetal oxide NaV2O5. Based on a cluster-model approach explicit expressions for the exchange integral and the Ramanoperator are given. It is demonstrated that a combination of the electronic-structure and the Dzyaloshinskii-Moriya interaction, allowed by symmetry in this material, are responsible for the finite Raman cross-section giving rise to both, oneand two-magnon scattering amplitudes.

Lattice vibrations ofα′−NaV2O5Popova1, Sushkov2, Климин3 et al. 2002Phys. Rev. B215120View full textAdd to dashboardCite

“…Subsequent structure redetermination for the HT phase of α ′ -NaV 2 O 5 [2][3][4][5] does not, however, allow to ascribe E a polarized spectral continuum to a pure twospinon absorption. Symmetry considerations show that for both HT-and LT-structure of α ′ -NaV 2 O 5 the two-spinon (two-magnon) absorption is allowed only in E c polarization [33,34]. Probably, a weak FIR absorption background observed in this polarization results just from the two-spinon absorption.…”

“…The transitions between the singlet ground state and the excited triplet state are forbidden (∆S = 1). The Dzyaloshinsky-Moria (DM) interaction with DM vector along the c-axis breaks the selection rule for ESR (and FIR) E c transitions in α ′ -NaV 2 O 5 [37,34]. Recently, it has been shown theoretically [34] that for α ′ -NaV 2 O 5 the DM interaction results in finite Raman cross-section for both one-and two-magnon scattering processes.…”

“…The Dzyaloshinsky-Moria (DM) interaction with DM vector along the c-axis breaks the selection rule for ESR (and FIR) E c transitions in α ′ -NaV 2 O 5 [37,34]. Recently, it has been shown theoretically [34] that for α ′ -NaV 2 O 5 the DM interaction results in finite Raman cross-section for both one-and two-magnon scattering processes. A single-magnon Raman line of this type should show no splitting in an external magnetic field parallel to the c-axis but should split into two branches for a field perpendicular to the c-axis.…”

Spin-gap mode in the charge-ordered phase ofNaV2O5studied by Raman scattering under high pressures

“…͑52͒ should be taken into consideration. 40 However, the above result does not change, taking Eqs. ͑53͒ and ͑54͒ into account.…”

“…It is very weak and detectable under the resonant condition, and splits into two peaks when magnetic fields are applied parallel to the b and c axes, but it neither shifts nor splits when a magnetic field is parallel to the a axis. Valentí et al 40 theoretically studied Raman scattering in quasi-one-dimensional antiferromagnetic spin chains considering the Dzyaloshinskii-Moriya ͑DM͒ interaction. They concluded that a single magnon excitation probed by Raman scattering should show no splitting in external magnetic field parallel to the DM vector D and it should split into two branches for a field perpendicular to the DM vector.…”