Fava Michele, Coldea Radu, Parameswaran S A
Rudolf Peierls Centre for Theoretical Physics, Department of Physics, University of Oxford, Oxford OX1 3PU, United Kingdom.
Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, United Kingdom.
Proc Natl Acad Sci U S A. 2020 Oct 13;117(41):25219-25224. doi: 10.1073/pnas.2007986117. Epub 2020 Sep 25.
We construct a microscopic spin-exchange Hamiltonian for the quasi-one-dimensional (1D) Ising magnet [Formula: see text] that captures detailed and hitherto-unexplained aspects of its dynamic spin structure factor. We perform a symmetry analysis that recalls that an individual Ising chain in this material is buckled, with two sites in each unit cell related by a glide symmetry. Combining this with numerical simulations benchmarked against neutron scattering experiments, we argue that the single-chain Hamiltonian contains a staggered spin-exchange term. We further argue that the transverse-field-tuned quantum critical point in [Formula: see text] corresponds to breaking this glide symmetry, rather than an on-site Ising symmetry as previously believed. This gives a unified microscopic explanation of the dispersion of confined states in the ordered phase and quasiparticle breakdown in the polarized phase at high transverse field.
我们为一维准 Ising 磁体[公式：见原文]构建了一个微观自旋交换哈密顿量，该哈密顿量捕捉到了其动态自旋结构因子中详细且迄今未得到解释的方面。我们进行了对称性分析，该分析表明这种材料中的单个 Ising 链是弯曲的，每个晶胞中有两个通过滑移对称性相关的位点。将此与针对中子散射实验进行基准测试的数值模拟相结合，我们认为单链哈密顿量包含一个交错自旋交换项。我们进一步认为，[公式：见原文]中横向场调谐的量子临界点对应于这种滑移对称性的破坏，而不是如先前所认为的在位 Ising 对称性的破坏。这为有序相中受限态的色散以及高横向场下极化相中准粒子崩溃提供了一个统一的微观解释。
