近日，瑞士保罗谢勒研究所的Romain Sibille及其研究团队取得一项新进展。他们揭示了量子自旋冰中分数物质与涌现规范场耦合的证据。相关研究成果已于2024年12月12日在国际知名学术期刊《自然—物理学》上发表。
本研究探讨了候选量子自旋冰材料Ce2Sn2O7的时间依赖性磁响应。研究人员发现了一个带隙谱，其特征在于一个阈值以及与背景量子电动力学场强耦合的，分数物质激发对的产生和传播理论相匹配的峰值。中子光谱数据中的多个峰值是量子自旋冰所谓π-磁通量相的特定标志，为三维量子自旋液体中的分数化提供了光谱证据。
据悉，电子自旋可以形成名为量子自旋液体的长程纠缠凝聚态。这类状态有望在阻挫磁体中形成，而阻挫磁体在降至零温度时也不会表现出对称性破缺的有序态。量子自旋冰是一个理论上已得到充分证实的例子，它由一种涌现的量子电动力学描述，其准粒子激发的行为类似于光子和带分数电荷的物质。然而，在阻挫磁体中，仍然难以找到令人信服的实验证据来证明，量子自旋液体基态及其分数激发的存在。
附：英文原文
Title: Evidence for fractional matter coupled to an emergent gauge field in a quantum spin ice
Author: Pore, Victor, Yan, Han, Desrochers, Flix, Petit, Sylvain, Lhotel, Elsa, Appel, Markus, Ollivier, Jacques, Kim, Yong Baek, Nevidomskyy, Andriy H., Sibille, Romain
Issue&Volume: 2024-12-12
Abstract: Electronic spins can form long-range entangled phases of condensed matter named quantum spin liquids. They are expected to form in frustrated magnets that do not exhibit symmetry-breaking order down to zero temperature. Quantum spin ice is a theoretically well-established example described by an emergent quantum electrodynamics, with quasiparticle excitations behaving like photons and fractionally charged matter. However, in frustrated magnets it remains difficult to establish convincing experimental evidence for quantum spin liquid ground states and their fractional excitations. Here we study the time-dependent magnetic response of the candidate quantum spin ice material Ce2Sn2O7. We find a gapped spectrum that features a threshold and peaks that match theories for pair production and propagation of fractional matter excitations strongly coupled to a background quantum electrodynamic field. The multiple peaks in our neutron spectroscopy data are a specific signature of the so-called π-flux phase of quantum spin ice, providing spectroscopic evidence for fractionalization in a three-dimensional quantum spin liquid.
DOI: 10.1038/s41567-024-02711-w
Source: https://www.nature.com/articles/s41567-024-02711-w