Spin Supersolid State and Giant Cooling Effect in a Triangular Lattice Antiferromagnet

ORAL

Abstract

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, constituting a quantum magnetic analog of supersolid. Recently, using tensor network approaches [1,2], we determine the microscopic spin Hamiltonian of a Co-based quantum antiferromagnet Na2BaCo(PO4)2, and find that it represents a rare and nearly perfect realization of the easy-axis triangular lattice Heisenberg model. It therefore supports the long-sought spin supersolid state [3]. Furthermore, together with experimental collaborators, we find evidence for such exotic quantum spin state and discover a significant entropic effect related to this unique and highly fluctuating quantum spin state [4].

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Publication: [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).

Presenters

  • Wei Li

    BeiHang University

Authors

  • Wei Li

    BeiHang University