Chen Gang V
International Center for Quantum Materials, School of Physics, <a href="https://ror.org/02v51f717">Peking University</a>, Beijing 100871, China and <a href="https://ror.org/03jn38r85">Collaborative Innovation Center of Quantum Matter</a>, 100871 Beijing, China.
Phys Rev Lett. 2024 Sep 27;133(13):136703. doi: 10.1103/PhysRevLett.133.136703.
Motivated by the experiments on the triangular lattice bilayer colbaltate K_{2}Co_{2}(SeO_{3})_{3}, we consider an extended XXZ model to explore the underlying physics. The model is composed of interacting Co^{2+} dimers on the triangular lattice, where the Co^{2+} ion provides an effective spin-1/2 local moment via the spin-orbit coupling and the crystal field effect. The intradimer interaction is dominant and would simply favor the local spin singlet, and the interdimer interactions compete with the interdimer interaction, leading to rich behaviors. With the easy-axis anisotropy, it is shown that, in the ground state manifold of the intradimer Ising interaction, the system realizes an effective quantum Ising model, where the ground state is either a three-sublattice order with a mixture of antiferromagnetic Ising order and a valence-bond spin singlet or Ising disordered. The finite temperature regime realizes the Berezinskii-Kosterlitz-Thouless physics. To explore the full excitations, we incorporate the excited state manifold of the intradimer Ising interaction and establish the emergent Kugel-Khomskii physics. Thus, the triangular lattice bilayer colbaltate is an excellent platform to explore the interplay between geometrical frustration and anisotropic interactions as well as the emergent effective models and the resulting physics.
受三角晶格双层钴酸盐(K_{2}Co_{2}(SeO_{3})_{3})实验的启发，我们考虑一个扩展的XXZ模型来探索其潜在物理机制。该模型由三角晶格上相互作用的(Co^{2 +})二聚体组成，其中(Co^{2 +})离子通过自旋轨道耦合和晶体场效应提供一个有效的自旋(-1/2)局域矩。二聚体内相互作用占主导，倾向于形成局域自旋单重态，而二聚体间相互作用相互竞争，导致丰富的行为。在易轴各向异性情况下，结果表明，在二聚体内伊辛相互作用的基态流形中，系统实现了一个有效的量子伊辛模型，其基态要么是具有反铁磁伊辛序和价键自旋单重态混合的三晶格序，要么是伊辛无序态。有限温度区域实现了贝雷津斯基 - 科斯特利茨 - Thouless物理机制。为了探索完整的激发态，我们纳入了二聚体内伊辛相互作用的激发态流形，并建立了涌现的库格尔 - 霍姆斯基物理机制。因此，三角晶格双层钴酸盐是探索几何阻挫与各向异性相互作用之间的相互作用以及涌现的有效模型和由此产生的物理机制的一个优秀平台。
