Jang Myeongjin, Lee Sol, Cantos-Prieto Fernando, Košić Ivona, Li Yue, McCray Arthur R C, Jung Min-Hyoung, Yoon Jun-Yeong, Boddapati Loukya, Deepak Francis Leonard, Jeong Hu Young, Phatak Charudatta M, Santos Elton J G, Navarro-Moratalla Efrén, Kim Kwanpyo
Department of Physics, Yonsei University, Seoul, Republic of Korea.
Center for Nanomedicine, Institute for Basic Science (IBS), Seoul, Republic of Korea.
Nat Commun. 2024 Jul 15;15(1):5925. doi: 10.1038/s41467-024-50314-z.
Van der Waals (vdW) stacking is a powerful technique to achieve desired properties in condensed matter systems through layer-by-layer crystal engineering. A remarkable example is the control over the twist angle between artificially-stacked vdW crystals, enabling the realization of unconventional phenomena in moiré structures ranging from superconductivity to strongly correlated magnetism. Here, we report the appearance of unusual 120° twisted faults in vdW magnet CrI crystals. In exfoliated samples, we observe vertical twisted domains with a thickness below 10 nm. The size and distribution of twisted domains strongly depend on the sample preparation methods, with as-synthesized unexfoliated samples showing tenfold thicker domains than exfoliated samples. Cooling induces changes in the relative populations among different twisting domains, rather than the previously assumed structural phase transition to the rhombohedral stacking. The stacking disorder induced by sample fabrication processes may explain the unresolved thickness-dependent magnetic coupling observed in CrI.
范德华（vdW）堆叠是一种通过逐层晶体工程在凝聚态系统中实现所需特性的强大技术。一个显著的例子是对人工堆叠的vdW晶体之间的扭转角进行控制，从而能够在从超导到强关联磁性的莫尔结构中实现非常规现象。在此，我们报告了vdW磁体CrI晶体中出现异常的120°扭曲缺陷。在剥离样品中，我们观察到厚度低于10nm的垂直扭曲畴。扭曲畴的尺寸和分布强烈依赖于样品制备方法，合成的未剥离样品显示出比剥离样品厚十倍的畴。冷却引起不同扭曲畴之间相对数量的变化，而不是先前假设的向菱面体堆叠的结构相变。样品制备过程引起的堆叠无序可能解释了在CrI中观察到的尚未解决的厚度依赖性磁耦合。
