该研究团队使用相分辨相干声子光谱(CPS)技术，成功揭示了vdW反铁磁体FePS3中隐藏的自旋晶格耦合，这种耦合避开了其他相不敏感的传统探针，如拉曼散射和X射线散射。通过对比分析和解析计算，他们证明了FePS3中的磁序通过部分填充的t2g轨道与三角畸变选择性地耦合。这种磁弹性耦合在磁序和晶格参数上是线性的，使得这些畸变无法用非弹性散射技术探测。该研究结果不仅捕获了FePS3中的自旋晶格耦合，而且还建立了相位分辨CPS作为研究隐藏相互作用的工具。
据介绍，不同自由度之间的强相互作用会导致具有复杂序参量和涌现的集体激励的奇异物态。传统的技术，如散射和输运，可以探测这些激励的振幅，但通常对相位不敏感。因此，需要一种新的具有相位灵敏度的方法来理解具有相位调制和相互作用的基态，这些基态与集体模的相位耦合。
附：英文原文
Title: Coherent detection of hidden spin–lattice coupling in a van der Waals antiferromagnet
Author: Ergeen, Emre, Ilyas, Batyr, Kim, Junghyun, Park, Jaena, Yilmaz, Mehmet Burak, Luo, Tianchuang, Xiao, Di, Okamoto, Satoshi, Park, Je-Geun, Gedik, Nuh
Issue&Volume: 2023-3-14
Abstract: Strong interactions between different degrees of freedom lead to exotic phases of matter with complex order parameters and emergent collective excitations. Conventional techniques, such as scattering and transport, probe the amplitudes of these excitations, but they are typically insensitive to phase. Therefore, novel methods with phase sensitivity are required to understand ground states with phase modulations and interactions that couple to the phase of collective modes. Here, by performing phase-resolved coherent phonon spectroscopy (CPS), we reveal a hidden spin–lattice coupling in a vdW antiferromagnet FePS3 that eluded other phase-insensitive conventional probes, such as Raman and X-ray scattering. With comparative analysis and analytical calculations, we directly show that the magnetic order in FePS3 selectively couples to the trigonal distortions through partially filled t2g orbitals. This magnetoelastic coupling is linear in magnetic order and lattice parameters, rendering these distortions inaccessible to inelastic scattering techniques. Our results not only capture the elusive spin–lattice coupling in FePS3 but also establish phase-resolved CPS as a tool to investigate hidden interactions.
DOI: 10.1073/pnas.2208968120
Source: https://www.pnas.org/doi/10.1073/pnas.2208968120