Magnetic order and disorder in a quasi-two-dimensional quantum Heisenberg antiferromagnet with randomized exchange
Physical Review B American Physical Society 102:17 (2020) 174429
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.From magnetic order to quantum disorder in the Zn-barlowite series of S = 1/2 kagomé antiferromagnets
npj Quantum Materials Springer Nature 5:1 (2020) 74
Magnetism and Néel skyrmion dynamics in GaV4S8-ySey
Physical Review Research American Physical Society (APS) 2:3 (2020) 032001
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