Takahashi Hiroto, Hsu Chun-Chih, Jerzembeck Fabian, Murphy Jack, Ward Jonathan, Enright Jack D, Knapp Jan, Puphal Pascal, Isobe Masahiko, Matsumoto Yosuke, Takagi Hidenori, Davis J C Séamus, Blundell Stephen J
Department of Physics, Clarendon Laboratory, University of Oxford, Oxford OX1 3PU, United Kingdom.
Max Planck Institute for Chemical Physics of Solids, Dresden D-01187, Germany.
Proc Natl Acad Sci U S A. 2025 Mar 25;122(12):e2422498122. doi: 10.1073/pnas.2422498122. Epub 2025 Mar 18.
An emerging concept for identification of different types of spin liquids [C. Broholm , , eaay0668 (2020)] is through the use of spontaneous spin noise [S. Chatterjee, J. F. Rodriguez-Nieva, E. Demler, , 104425 (2019)]. Here, we develop spin noise spectroscopy for spin liquid studies by considering CaCrO, a material hypothesized to be either a quantum or a spiral spin liquid (SSL). By enhancing techniques introduced for magnetic monopole noise studies [R. Dusad , , 234-239 (2019)], we measure the time and temperature dependence of spontaneous flux [Formula: see text] and thus magnetization [Formula: see text] of CaCrO samples. The resulting power spectral density of magnetization noise [Formula: see text] reveals intense spin fluctuations with [Formula: see text] and [Formula: see text]. Both the variance [Formula: see text] and the correlation function [Formula: see text] of this spin noise undergo crossovers at a temperature [Formula: see text]. While predictions for quantum spin liquids are inconsistent with this phenomenology, those from Monte-Carlo simulations of a two-dimensional (2D) SSL state in CaCrO yield overall quantitative correspondence with the measured frequency and temperature dependences of [Formula: see text], and [Formula: see text], thus indicating that CaCrO is an SSL.
一种用于识别不同类型自旋液体的新兴概念[C. 布罗霍尔姆等人，eaay0668 (2020)]是通过使用自发自旋噪声[S. 查特吉、J. F. 罗德里格斯 - 涅瓦、E. 德姆勒等人，104425 (2019)]。在此，我们通过考虑CaCrO（一种被假设为量子或螺旋自旋液体（SSL）的材料）来开发用于自旋液体研究的自旋噪声光谱学。通过改进用于磁单极子噪声研究的技术[R. 杜萨德等人，234 - 239 (2019)]，我们测量了CaCrO样品自发通量[公式：见原文]以及因此的磁化强度[公式：见原文]的时间和温度依赖性。由此得到的磁化噪声功率谱密度[公式：见原文]揭示了在[公式：见原文]和[公式：见原文]处存在强烈的自旋涨落。这种自旋噪声的方差[公式：见原文]和关联函数[公式：见原文]在温度[公式：见原文]处都发生了转变。虽然量子自旋液体的预测与这种现象学不一致，但来自CaCrO中二维（2D）SSL态的蒙特卡罗模拟的预测与所测量的[公式：见原文]、[公式：见原文]的频率和温度依赖性总体上在定量上相符，从而表明CaCrO是一种SSL。
