Song Tiancheng, Fei Zaiyao, Yankowitz Matthew, Lin Zhong, Jiang Qianni, Hwangbo Kyle, Zhang Qi, Sun Bosong, Taniguchi Takashi, Watanabe Kenji, McGuire Michael A, Graf David, Cao Ting, Chu Jiun-Haw, Cobden David H, Dean Cory R, Xiao Di, Xu Xiaodong
Department of Physics, University of Washington, Seattle, WA, USA.
Department of Physics, Columbia University, New York, NY, USA.
Nat Mater. 2019 Dec;18(12):1298-1302. doi: 10.1038/s41563-019-0505-2. Epub 2019 Oct 28.
The physical properties of two-dimensional van der Waals crystals can be sensitive to interlayer coupling. For two-dimensional magnets, theory suggests that interlayer exchange coupling is strongly dependent on layer separation while the stacking arrangement can even change the sign of the interlayer magnetic exchange, thus drastically modifying the ground state. Here, we demonstrate pressure tuning of magnetic order in the two-dimensional magnet CrI. We probe the magnetic states using tunnelling and scanning magnetic circular dichroism microscopy measurements. We find that interlayer magnetic coupling can be more than doubled by hydrostatic pressure. In bilayer CrI, pressure induces a transition from layered antiferromagnetic to ferromagnetic phase. In trilayer CrI, pressure can create coexisting domains of three phases, one ferromagnetic and two antiferromagnetic. The observed changes in magnetic order can be explained by changes in the stacking arrangement. Such coupling between stacking order and magnetism provides ample opportunities for designer magnetic phases and functionalities.
二维范德华晶体的物理性质可能对层间耦合敏感。对于二维磁体，理论表明层间交换耦合强烈依赖于层间距，而堆叠排列甚至可以改变层间磁交换的符号，从而极大地改变基态。在此，我们展示了二维磁体CrI中磁序的压力调谐。我们使用隧穿和扫描磁圆二色性显微镜测量来探测磁态。我们发现，通过静水压力，层间磁耦合可以增加一倍以上。在双层CrI中，压力诱导从层状反铁磁相转变为铁磁相。在三层CrI中，压力可以产生三相共存的畴，一个铁磁相和两个反铁磁相。观察到的磁序变化可以通过堆叠排列的变化来解释。这种堆叠顺序与磁性之间的耦合为设计磁性相和功能提供了充足的机会。
