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Magnetic order and disorder in a quasi-two-dimensional quantum Heisenberg antiferromagnet with randomized exchange

Xiao, F.; Blackmore, W.J.A.; Huddart, B.M.; Gomilšek, M.; Hicken, T.J.; Baines, C.; Baker, P.J.; Pratt, F.L.; Blundell, S.J.; Lu, H.; Singleton, J.; Gawryluk, D.; Turnbull, M.M.; Krämer, K.W.; Goddard, P.A.; Lancaster, T.

Magnetic order and disorder in a quasi-two-dimensional quantum Heisenberg antiferromagnet with randomized exchange Thumbnail


Authors

F. Xiao

W.J.A. Blackmore

M. Gomilšek

C. Baines

P.J. Baker

F.L. Pratt

S.J. Blundell

H. Lu

J. Singleton

D. Gawryluk

M.M. Turnbull

K.W. Krämer

P.A. Goddard



Abstract

We present an investigation of the effect of randomizing exchange coupling strengths in the S = 1/2 square lattice quasi-two-dimensional quantum Heisenberg antiferromagnet (QHAF) (QuinH)2Cu(ClxBr1−x )4 · 2H2O (QuinH = Quinolinium, C9H8N+), with 0 x 1. Pulsed-field magnetization measurements allow us to estimate an effective in-plane exchange strength J in a regime where exchange fosters short-range order, while the temperature TN at which long-range order (LRO) occurs is found using muon-spin relaxation, allowing us to construct a phase diagram for the series. We evaluate the effectiveness of disorder in suppressing TN and the ordered moment size, and we find an extended disordered phase in the region 0.4 x 0.8 where no magnetic order occurs. The observed critical substitution levels are accounted for by an energetics-based competition between different local magnetic orders. Furthermore, we demonstrate experimentally that the ground-state disorder is driven by quantum effects of the exchange randomness, which is a feature that has been predicted theoretically and has implications for other disordered quasi-two-dimensional QHAFs.

Citation

Xiao, F., Blackmore, W., Huddart, B., Gomilšek, M., Hicken, T., Baines, C., …Lancaster, T. (2020). Magnetic order and disorder in a quasi-two-dimensional quantum Heisenberg antiferromagnet with randomized exchange. Physical Review B, 102(17), Article 174429. https://doi.org/10.1103/physrevb.102.174429

Journal Article Type Article
Acceptance Date Oct 26, 2020
Online Publication Date Nov 17, 2020
Publication Date Nov 1, 2020
Deposit Date Nov 18, 2020
Publicly Available Date Oct 26, 2021
Journal Physical Review B
Print ISSN 2469-9950
Electronic ISSN 2469-9969
Publisher American Physical Society
Peer Reviewed Peer Reviewed
Volume 102
Issue 17
Article Number 174429
DOI https://doi.org/10.1103/physrevb.102.174429

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© 2020 American Physical Society







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