Hong, WenshanLiu, LuLiu, ChangMa, XiaoyanKoda, AkihiroLi, XinSong, JianmingYang, WenyunYang, JinboCheng, PengZhang, HongxiaBao, WeiMa, XiaobaiChen, DongfengSun, KaiGuo, WenanLuo, HuiqianSandvik, Anders W.Li, Shiliang2021-07-292021-07-292021-01-22Wenshan Hong, Lu Liu, Chang Liu, Xiaoyan Ma, Akihiro Koda, Xin Li, Jianming Song, Wenyun Yang, Jinbo Yang, Peng Cheng, Hongxia Zhang, Wei Bao, Xiaobai Ma, Dongfeng Chen, Kai Sun, Wenan Guo, Huiqian Luo, Anders W Sandvik, Shiliang Li. 2021. "Extreme Suppression of Antiferromagnetic Order and Critical Scaling in a Two-Dimensional Random Quantum Magnet.." Phys Rev Lett, Volume 126, Issue 3, pp. 037201 - ?. https://doi.org/10.1103/PhysRevLett.126.0372011079-7114https://hdl.handle.net/2144/42804Sr_2CuTeO_6 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 Sr_2CuTe_1-xW_xO_6 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/r^2 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 Sr_2CuTe_1-x W_x O_6, the μSR relaxation rate exhibits quantum critical scaling with a large dynamic exponent, z≈3, consistent with a random-singlet state.p. 037201en-USGeneral physicsMathematical sciencesPhysical sciencesEngineeringArticle10.1103/PhysRevLett.126.0372010000-0002-5638-4619 (Sandvik, Anders W)563977