Abstract
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.
| Original language | English |
|---|---|
| Article number | 037201 |
| Journal | Physical Review Letters |
| Volume | 126 |
| Issue number | 3 |
| Online published | 19 Jan 2021 |
| DOIs | |
| Publication status | Published - 22 Jan 2021 |
Publisher's Copyright Statement
- COPYRIGHT TERMS OF DEPOSITED FINAL PUBLISHED VERSION FILE: Hong, W., Liu, L., Liu, C., Ma, X., Koda, A., Li, X., Song, J., Yang, W., Yang, J., Cheng, P., Zhang, H., Bao, W., Ma, X., Chen, D., Sun, K., Guo, W., Luo, H., Sandvik, A. W., & Li, S. (2021). Extreme Suppression of Antiferromagnetic Order and Critical Scaling in a Two-Dimensional Random Quantum Magnet. Physical Review Letters, 126(3), Article 037201. https://doi.org/10.1103/PhysRevLett.126.037201 The copyright of this article is owned by American Physical Society.