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Frustration and Dzyaloshinsky-Moriya anisotropy in the kagome francisites Cu3Bi(SeO3)2O2X (X = Br, Cl)

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journal contribution
posted on 07.08.2018, 12:35 by Ioannis RousochatzakisIoannis Rousochatzakis, Johannes Richter, Ronald Zinke, Alexander A. Tsirlin
We investigate the antiferromagnetic canting instability of the spin-1/2 kagome ferromagnet, as realized in the layered cuprates Cu3Bi(SeO3)2O2X (X = Br, Cl). While the local canting can be explained in terms of competing exchange interactions, the direction of the ferrimagnetic order parameter fluctuates strongly even at short distances on account of frustration which gives rise to an infinite ground state degeneracy at the classical level. In analogy with the kagome antiferromagnet, the accidental degeneracy is fully lifted only by nonlinear 1/S corrections, rendering the selected uniform canted phase very fragile even for spins-1/2, as shown explicitly by coupled-cluster calculations. To account for the observed ordering, we show that the minimal description of these systems must include the microscopic Dzyaloshinsky-Moriya interactions, which we obtain from density-functional band-structure calculations. The model explains all qualitative properties of the kagome francisites, including the detailed nature of the ground state and the anisotropic response under a magnetic field. The predicted magnon excitation spectrum and quantitative features of the magnetization process call for further experimental investigations of these compounds.

Funding

A.T. was supported by the ESF through the Mobilitas Grant MTT77 and by the IUT23-3 grant of the Estonian Research Council.

History

School

  • Science

Department

  • Physics

Published in

Physical Review B - Condensed Matter and Materials Physics

Volume

91

Issue

2

Citation

ROUSOCHATZAKIS, I. ... et al, 2015. Frustration and Dzyaloshinsky-Moriya anisotropy in the kagome francisites Cu3Bi(SeO3)2O2X (X = Br, Cl). Physical Review B, 91 (2), 024416.

Publisher

© American Physical Society

Version

AM (Accepted Manuscript)

Publisher statement

This work is made available according to the conditions of the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) licence. Full details of this licence are available at: https://creativecommons.org/licenses/by-nc-nd/4.0/

Publication date

2015

Notes

This paper was published in the journal Physical Review B and the definitive published version is available at https://doi.org/10.1103/PhysRevB.91.024416.

ISSN

2469-9950

eISSN

2469-9969

Language

en

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