Spectroscopic Evidence of Supersolids in Quantum Ising Magnet K2Co(SeO3)2*

ORAL

Abstract

We report the neutron scattering results for the spin- 1/2 triangular-lattice antiferromagnet, K2Co(SeO3)2, which features nearest-neighbor Ising-like interactions with Jz = 2.96(2) meV and Jxy = 0.21(3) meV. For temperatures below 15 K, neutron spectroscopy reveals the gradual development of solidity, indicated by a quasi-two-dimensional √3 × √3 magnetic order associated with Z3 symmetry breaking. Below 0.3 K, the emergence of a Goldstone mode from low-energy continuum scattering provides evidence of superfluidity associated with breaking spin rotational U(1) symmetry. Notably, the presence of flat bands of excitations at quantized energies (ℏω = nJz, n = 0, 1, 2, 3) is a hallmark of the spatially modulated <Sz> on a triangular lattice, distinguishing K2Co(SeO3)2 from existing candidates. Our work demonstrates that K2Co(SeO3)2 is a spectacular example of a spin- 1/2 triangular-lattice quantum Ising magnet and provides spectroscopic evidence of zero-field supersolidity on a triangular lattice.

**This work was supported by the Gordon and Betty Moore Foundation EPIQS program under GBMF9456 and by the U.S. DOE Office of Science, Office of Basic Energy Sciences, Materials Sciences and Engineering Division DE-SC0024469.

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Publication: Chen, Tong, et al. "Phase Diagram and Spectroscopic Evidence of Supersolids in Quantum Ising Magnet K $ _2 $ Co (SeO $ _3 $) $ _2$." arXiv preprint arXiv:2402.15869 (2024).

Presenters

  • Tong Chen

    • Johns Hopkins University

Authors

  • Tong Chen

    • Johns Hopkins University

  • Alireza Ghasemi

    • Johns Hopkins University

  • Junyi Zhang

    • Johns Hopkins University

  • Liyu Shi

    • Johns Hopkins University

  • Zhenisbek Tagay

    • Johns Hopkins University

  • Shiyuan Gao

    • Johns Hopkins University

  • Youzhe Chen

    • University of California, Berkeley

  • Lei Chen

    • Stony Brook University
    • Rice University

  • Eun Sang Choi

    • National High Magnetic Field Lab
    • National High Magnetic Field Laboratory
    • National High Magnetic Field Laboratory, Florida State University

  • Marcelo Jaime

    • Physikalisch-Technische Bundesanstalt

  • Minseong Lee

    • National High Magnetic Field Laboratory

  • Yiqing Hao

    • Oak Ridge National Laboratory

  • Huibo Cao

    • Oak Ridge National Laboratory

  • Barry Winn

    • Oak Ridge National Laboratory

  • Andrey A Podlesnyak

    • Oak Ridge National Laboratory

  • Ruidan Zhong

    • Princeton University
    • Shanghai Jiaotong University
    • Shanghai Jiao Tong University

  • Xianghan Xu

    • University of Minnesota, Twin Cities
    • Princeton University

  • Peter N Armitage

    • Johns Hopkins University

  • Robert J Cava

    • Princeton University

  • Collin L Broholm

    • Johns Hopkins University