近日，美国斯坦福大学Feldman, Benjamin E.团队报道了扭曲半导体均匀层中的磁霍夫施塔特级联。这一研究成果发表在2025年10月21日出版的《自然—物理学》杂志上。
过渡金属二硫系莫尔纳米层已经成为一个磁性、强相关性和拓扑结构交织在一起的平台。在大磁场中，这些系统中具有不同自旋态的能量排列是由强塞曼分裂和霍夫施塔特蝴蝶光谱结构决定的，但后者很难通过实验来探测。
研究组应用局部热力学测量，观察到在扭曲WSe2均匀层中磁相变的级联。研究组将这些跃迁解释为单个霍夫施塔特子带的填充，使他们能够提取单个自旋霍夫施塔特谱的结构和连通性。磁跃迁的开始与扭转角无关，表明组分层的交换相互作用仅受莫尔阱势的微弱改变。相反，磁跃迁与相应填充时绝缘状态的变化有关。该工作实现了霍夫施塔特蝴蝶的自旋分辨测量，尽管有重叠的状态，并解开了材料特性和摩尔超晶格在稳定相关基态方面的作用。
附：英文原文
Title: Magnetic Hofstadter cascade in a twisted semiconductor homobilayer
Author: Foutty, Benjamin A., Reddy, Aidan P., Kometter, Carlos R., Watanabe, Kenji, Taniguchi, Takashi, Devakul, Trithep, Feldman, Benjamin E.
Issue&Volume: 2025-10-21
Abstract: Transition metal dichalcogenide moiré homobilayers have emerged as a platform in which magnetism, strong correlations and topology are intertwined. In a large magnetic field, the energetic alignment of states with different spin in these systems is dictated by both strong Zeeman splitting and the structure of the Hofstadter’s butterfly spectrum, yet the latter has been difficult to probe experimentally. Here we observe a cascade of magnetic phase transitions in a twisted WSe2 homobilayer using local thermodynamic measurements. We interpret these transitions as the filling of individual Hofstadter subbands, enabling us to extract the structure and connectivity of the Hofstadter spectrum for a single spin. The onset of magnetic transitions is independent of twist angle, indicating that the exchange interactions of the component layers are only weakly modified by the moiré potential. By contrast, the magnetic transitions are associated with changes in the insulating states at commensurate filling. Our work achieves a spin-resolved measurement of Hofstadter’s butterfly despite overlapping states and disentangles the role of material properties and moiré superlattices in stabilizing the correlated ground states.
DOI: 10.1038/s41567-025-03083-5
Source: https://www.nature.com/articles/s41567-025-03083-5