TY - JOUR
T1 - Extreme Suppression of Antiferromagnetic Order and Critical Scaling in a Two-Dimensional Random Quantum Magnet
AU - Hong, Wenshan
AU - Liu, Lu
AU - Liu, Chang
AU - Ma, Xiaoyan
AU - Koda, Akihiro
AU - Li, Xin
AU - Song, Jianming
AU - Yang, Wenyun
AU - Yang, Jinbo
AU - Cheng, Peng
AU - Zhang, Hongxia
AU - Bao, Wei
AU - Ma, Xiaobai
AU - Chen, Dongfeng
AU - Sun, Kai
AU - Guo, Wenan
AU - Luo, Huiqian
AU - Sandvik, Anders W.
AU - Li, Shiliang
PY - 2021/1/22
Y1 - 2021/1/22
N2 - Sr2CuTeO6 is a square-lattice Néel antiferromagnet with superexchange between first-neighbor S =1/2 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 Sr2CuTe1-xWxO6 using neutron diffraction and μSR techniques, showing that the Néel order vanishes already at x=0.025±0.005. 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 1/r2 at temperature T=0. The associated logarithmic singularity leads to loss of order for any x>0. Order for small x>0 and T>0 is induced by weak interplane couplings. In the nonmagnetic phase of Sr2CuTe1-xWxO6, the μSR relaxation rate exhibits quantum critical scaling with a large dynamic exponent, z≈3, consistent with a random-singlet state.
AB - Sr2CuTeO6 is a square-lattice Néel antiferromagnet with superexchange between first-neighbor S =1/2 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 Sr2CuTe1-xWxO6 using neutron diffraction and μSR techniques, showing that the Néel order vanishes already at x=0.025±0.005. 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 1/r2 at temperature T=0. The associated logarithmic singularity leads to loss of order for any x>0. Order for small x>0 and T>0 is induced by weak interplane couplings. In the nonmagnetic phase of Sr2CuTe1-xWxO6, the μSR relaxation rate exhibits quantum critical scaling with a large dynamic exponent, z≈3, consistent with a random-singlet state.
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U2 - 10.1103/PhysRevLett.126.037201
DO - 10.1103/PhysRevLett.126.037201
M3 - RGC 21 - Publication in refereed journal
VL - 126
JO - Physical Review Letters
JF - Physical Review Letters
SN - 0031-9007
IS - 3
M1 - 037201
ER -