場所：オンライン（Zoom）
講師： Prof. Wei Li
所属： Institute of Theoretical Physics, Chinese Academy of Sciences
題目： Spin Supersolidity and Giant Magnetocaloric Effect in a Triangular Lattice Quantum Antiferromagnet
要旨：Supersolid is an exotic quantum state of matter that emerges near absolute zero temperature. The spin supersolid spontaneously breaks both the lattice translational and spin rotational symmetries, forming a quantum magnetic analog of supersolid. Recently, using tensor network approaches [1,2], we determined the microscopic spin Hamiltonian of a Co-based quantum antiferromagnet Na2BaCo(PO4)2. We discovered that it represents a rare and nearly perfect realization of the easy-axis triangular lattice Heisenberg model, and therefore supports the long-sought spin supersolid state [4]. We further predict theoretically and, in conjunction with experimental collaborators, observe a significant entropic effect related to this unique and highly fluctuating spin state - spin supersolid cooling [5].
[1] B.-B. Chen, L. Chen, Z. Chen, WL, and A. Weichselbaum, Exponential thermal tensor network approach for quantum lattice models. Phys. Rev. X 8, 031082 (2018).
[2] Q. Li, Y. Gao, Y.-Y. He, Y. Qi, B.-B. Chen, and WL, Tangent Space Approach for Thermal Tensor Network Simulations of the 2D Hubbard Model. Phys. Rev. Lett. 130, 226502 (2023).
[3] Y. Gao, Y. Fan, H. Li, [...], Y. Wan, and WL. Spin supersolidity in nearly ideal easy-axis triangular quantum antiferromagnet Na2BaCo(PO4)2. Npj Quantum Mater. 7, 89 (2022).
[4] J. Xiang, C. Zhang, Y. Gao, [...], W. Jin, WL, P. Sun, G. Su, Giant magnetocaloric effect in spin supersolid candidate Na2BaCo(PO4)2, Nature 625, 270–275 (2024).
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