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Experimental evidence of a change of exchange anisotropy sign with temperature in Zn-substituted Cu2OSeO3

Moody, S.H.; Nielsen, P.; Wilson, M.N.; Venero, D. Alba; Štefančič, A.; Balakrishnan, G.; Hatton, P.D.

Experimental evidence of a change of exchange anisotropy sign with temperature in Zn-substituted Cu2OSeO3 Thumbnail


Authors

Samuel Moody samuel.h.moody@durham.ac.uk
PGR Student Doctor of Philosophy

P. Nielsen

M.N. Wilson

D. Alba Venero

A. Štefančič

G. Balakrishnan



Abstract

We report small-angle neutron scattering from the conical state in a single crystal of Zn-substituted Cu 2 OSeO 3 . Using a 3D vector-field magnet to reorient the conical wave vector, our measurements show that the magnitude of the conical wave vector changes as a function of crystallographic direction. These changes are explained using the anisotropic exchange interaction (AEI) within the continuum model, whose magnitude in free-energy transitions from a maxima to a minima along the ⟨ 111 ⟩ and ⟨ 100 ⟩ crystallographic directions respectively. We further find that the AEI free-energy constant undergoes a change of sign from positive to negative with decreasing temperature. Unlike in the related compound FeGe, where similar behavior of the AEI induces a reorientation of the helical wave vector, we show that the zero field helical wave vector in ( Cu 0.98 Zn 0.02 ) 2 OSeO 3 remains along the ⟨ 100 ⟩ directions at all temperatures due to the competing fourth-order magnetocrystalline anisotropy becoming dominant at lower temperatures.

Citation

Moody, S., Nielsen, P., Wilson, M., Venero, D. A., Štefančič, A., Balakrishnan, G., & Hatton, P. (2021). Experimental evidence of a change of exchange anisotropy sign with temperature in Zn-substituted Cu2OSeO3. Physical Review Research, 3(4), Article 043149. https://doi.org/10.1103/physrevresearch.3.043149

Journal Article Type Article
Acceptance Date Oct 27, 2021
Online Publication Date Dec 1, 2021
Publication Date 2021
Deposit Date Jan 7, 2022
Publicly Available Date Jan 7, 2022
Journal Physical Review Research
Publisher American Physical Society
Peer Reviewed Peer Reviewed
Volume 3
Issue 4
Article Number 043149
DOI https://doi.org/10.1103/physrevresearch.3.043149

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http://creativecommons.org/licenses/by/4.0/

Copyright Statement
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI







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