Valence-bond-glass state with a singlet gap in the spin-1/2 square-lattice random J(1)-J(2) Heisenberg antiferromagnet Sr2CuTe1-xWxO6

Article

关键词: QUANTUM ANTIFERROMAGNETS;    TRIANGULAR-LATTICE;    PHASE-TRANSITIONS;    MODEL;    EXPANSION;    LIQUIDS;    SYSTEMS;    ORDER;   

DOI  :  10.1103/PhysRevB.98.054422

来源: SCIE

【 摘 要 】

The double-perovskite compounds Sr2CuTeO6 and Sr2CuWO6 are magnetically described as quasi-two dimensional spin-1/2 square-lattice J(1) - J(2) Heisenberg antiferromagnets with predominant J(1) and J(2) exchange interactions, respectively. We report the low-temperature magnetic properties of Sr2CuTe1-xWxO6 with random ness in the magnitudes of J(1) and J(2). It was found that the low-temperature specific heat for 0.1 <= x <= 0.5 has a large component proportional to the temperature T above 1.2 K, although the low-temperature specific heat for the two parent systems is approximately proportional to T-3. With decreasing temperature below 1.2 K, the T-linear component decreases rapidly toward zero, which is insensitive to the magnetic field up to 9 T. This is suggestive of the singlet excitation decoupled from the magnetic field. The NMR spectrum for x = 0.2 exhibits no long-range order down to 1.8 K. These results indicate that the ground state of Sr2CuTe1-xWxO6 is a valence-bond-glass state with singlet gaps.

【 授权许可】

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