Structure, Spin Correlations, and Magnetism of the S = 1/2 Square-Lattice Antiferromagnet Sr2CuTe1-xWxO6 (0 ≤ x ≤ 1)

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A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
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Chemistry of Materials, Volume 36, issue 1
Quantum spin liquids are highly entangled magnetic states with exotic properties. The S = 1/2 square-lattice Heisenberg model is one of the foundational models in frustrated magnetism with a predicted, but never observed, quantum spin liquid state. Isostructural double perovskites Sr2CuTeO6 and Sr2CuWO6 are physical realizations of this model but have distinctly different types of magnetic order and interactions due to a d10/d0 effect. Long-range magnetic order is suppressed in the solid solution Sr2CuTe1-xWxO6 in a wide region of x = 0.05-0.6, where the ground state has been proposed to be a disorder-induced spin liquid. Here, we present a comprehensive neutron scattering study of this system. We show using polarized neutron scattering that the spin liquid-like x = 0.2 and x = 0.5 samples have distinctly different local spin correlations, which suggests that they have different ground states. Low-temperature neutron diffraction measurements of the magnetically ordered W-rich samples reveal magnetic phase separation, which suggests that the previously ignored interlayer coupling between the square planes plays a role in the suppression of magnetic order at x ≈ 0.6. These results highlight the complex magnetism of Sr2CuTe1-xWxO6 and hint at a new quantum critical point between 0.2 < x < 0.4.
Funding Information: The authors thank Dr. Lucy Clark, Dr. Ross Stewart, and Dr. Jennifer Graham for fruitful discussions. Dr. Clemens Ritter is thanked for technical assistance with the D20 data. O.H.J.M. is grateful for funding through Leverhulme Trust Early Career Fellowship ECF-2021-170. O.H.J.M. and E.J.C. acknowledge support from the Leverhulme Trust Research Project Grant RPG-2017-109. E.F. and H.M.R. acknowledge funding from the European Research Council through the Synergy Network HERO (grant no. 810451). The work of J.A.M.P. was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division. The authors thank the Science and Technology Facilities Council for beamtime allocated at ISIS (proposal number RB1810107). We acknowledge Diamond Light Source for access to beamline I15-1 XPDF within the joint (i15-1-POLARIS) PDF scheme under proposal CY21802. The authors are grateful for beamtime on the D20 high-flux diffractometer and the D7 diffuse scattering spectrometer at the Institut Laue-Langevin under proposals 5-31-2638 and 5-32-895. Publisher Copyright: © 2023 The Authors. Published by American Chemical Society.
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Mustonen , O H J , Fogh , E , Paddison , J A M , Mangin-Thro , L , Hansen , T , Playford , H Y , Diaz-Lopez , M , Babkevich , P , Vasala , S , Karppinen , M , Cussen , E J , Ro̷nnow , H M & Walker , H C 2024 , ' Structure, Spin Correlations, and Magnetism of the S = 1/2 Square-Lattice Antiferromagnet Sr 2 CuTe 1-x W x O 6 (0 ≤ x ≤ 1) ' , Chemistry of Materials , vol. 36 , no. 1 , pp. 501–513 .