Extreme Suppression of Antiferromagnetic Order and Critical Scaling in a Two-Dimensional Random Quantum Magnet
- 19 January 2021
- journal article
- research article
- Published by American Physical Society (APS) in Physical Review Letters
- Vol. 126 (3), 037201
- https://doi.org/10.1103/physrevlett.126.037201
Abstract
is a square-lattice Néel antiferromagnet with superexchange between first-neighbor Cu spins mediated by plaquette centered Te ions. Substituting Te by W, the affected impurity plaquettes have predominantly second-neighbor interactions, thus causing local magnetic frustration. Here we report a study of using neutron diffraction and techniques, showing that the Néel order vanishes already at . We explain this extreme order suppression using a two-dimensional Heisenberg spin model, demonstrating that a W-type impurity induces a deformation of the order parameter that decays with distance as at temperature . The associated logarithmic singularity leads to loss of order for any . Order for small and is induced by weak interplane couplings. In the nonmagnetic phase of , the relaxation rate exhibits quantum critical scaling with a large dynamic exponent, , consistent with a random-singlet state.
Funding Information
- National Natural Science Foundation of China (11734002, 11775021, 11874401, 11874401, 11674406, 11822411, 12061130200, 11227906)
- Chinese Academy of Sciences (XDB25000000, XDB07020000, XDB28000000, 2016004, XDB33010100)
- Natural Science Foundation of Beijing Municipality (JQ19002)
- National Science Foundation (DMR-1710170)
- Simons Foundation (511064)
- Boston University
- Beijing Normal University
- National Key R&D Program of China (2017YFA0302900, 2016YFA0300502, 2018YFA0704201, 2016YFA0300604, 2017YFA0303100)
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