School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan, 430074, China.
Department of Physics and Beijing Key Laboratory of Opto-electronic Functional Materials & Micro-nano Devices, Renmin University of China, Beijing, 100872, China.
Adv Mater. 2023 May;35(19):e2209931. doi: 10.1002/adma.202209931. Epub 2023 Mar 22.
Unraveling the magnetic order in iron chalcogenides and pnictides at atomic scale is pivotal for understanding their unconventional superconducting pairing mechanism, but is experimentally challenging. Here, by utilizing spin-polarized scanning tunneling microscopy, real-space spin contrasts are successfully resolved to exhibit atomically unidirectional stripes in Fe Se ultrathin films, the plausible closely related compound of bulk FeSe with ordered Fe-vacancies, which are grown by molecular beam epitaxy. As is substantiated by the first-principles electronic structure calculations, the spin contrast originates from a pair-checkerboard antiferromagnetic ground state with in-plane magnetization, which is modulated by a spin-lattice coupling. These measurements further identify three types of nanoscale antiferromagnetic domains with distinguishable spin contrasts, which are subject to thermal fluctuations into short-ranged patches at elevated temperatures. This work provides promising opportunities in understanding the emergent magnetic order and the electronic phase diagram for FeSe-derived superconductors.
在原子尺度上揭示铁的硫属化物和磷化物的磁有序对于理解其非常规超导配对机制至关重要，但实验上具有挑战性。在这里，通过利用自旋极化扫描隧道显微镜，成功分辨出实空间自旋对比，以展示在铁硒超薄薄膜中原子级单向条纹，这是与体相 FeSe 具有有序 Fe 空位的可能密切相关的化合物，这些薄膜是通过分子束外延生长的。正如第一性原理电子结构计算所证实的那样，自旋对比源自具有面内磁化的配对棋盘反铁磁基态，该基态由自旋-晶格耦合调制。这些测量进一步确定了三种具有可区分自旋对比的纳米级反铁磁畴，它们在高温下受到热波动的影响而成为短程斑块。这项工作为理解 FeSe 衍生超导体的新兴磁有序和电子相图提供了有希望的机会。
