Hanxiang Wu, Jianfeng Guo, Suonan Zhaxi, Hua Xu, Shuo Mi, Le Wang, Shanshan Chen, Rui Xu, Wei Ji, Fei Pang and Zhihai Cheng
Abstract:
As a unique 2D magnetic material with self-intercalated structure, Cr5Te8 exhibits many intriguing magnetic properties. While its ferromagnetism of Cr5Te8 has been previously reported, the research on its magnetic domain remains unexplored. Herein, we have successfully fabricated 2D Cr5Te8 nanosheets with controlled thickness and lateral size by chemical vapor deposition (CVD). Then magnetic property measurement system revealed Cr5Te8 nanosheets exhibiting intense out-of-plane ferromagnetism with a Curie temperature (TC) of 176 K. Significantly, we reported for the first time two magnetic domains: magnetic bubbles and thickness-dependent maze-like magnetic domains in our Cr5Te8 nanosheets by cryogenic magnetic force microscopy (MFM). The domain width of the maze-like magnetic domains increases rapidly with decreasing sample thickness, meanwhile domain contrast decreases. This indicates the dominate role of ferromagnetism shifts from dipolar interactions to magnetic anisotropy. Our research not only establishes a pathway for the controllable growth of 2D magnetic materials, but also points towards novel avenues for regulating magnetic phases and methodically tuning domain characteristics.
Yanyan Geng, Le Lei, Haoyu Dong, Jianfeng Guo, Shuo Mi, Yan Li, Li Huang, Fei Pang, Rui Xu, Weichang Zhou, Zheng Liu, Wei Ji, and Zhihai Cheng
Abstract:
The layered transition metal dichalcogenide 1T−TaS2 has evoked great interest owing to its particularly rich electronic phase diagram including different charge density wave (CDW) phases. However, few studies have focused on its hysteretic electronic phase transitions based on the in-depth discussion of the delicate interplay among temperature-dependent electronic interactions. Here, we report a sequence of spatial electronic phase transitions in the hysteresis temperature range (160–230 K) of 1T−TaS2 via variable-temperature scanning tunneling microscopy. Several emergent electronic states are investigated at multiscale during the commensurate CDW–triclinic CDW (CCDW-TCDW) phase transitions: a spotty-CDW state above ∼160K, a network-CDW (NCDW) state above ∼180K during the warmup process, a belt-TCDW state below ∼230K, a NCDW state below ∼200K, and finally a mosaic-CDW state below ∼160K during cooldown from the TCDW phase. These emergent electronic states are associated with the delicate temperature-dependent competition and/or cooperation of stacking-dependent interlayer interactions, intralayer electron-electron correlations, and electron-phonon (e−ph) coupling of 1T−TaS2. Our results not only provide insight to understand the hysteretic electronic phase transitions in the correlated CDW state, but also pave a way to realize more exotic quantum states by accurately and effectively tuning various interior interactions in correlated materials.
Peigen Li, Nanshu Liu, Jihai Zhang, Shenwei Chen, Xuhan Zhou, Donghui Guo, Cong Wang, Wei Ji, and Dingyong Zhong
Abstract:
Single-layer heterostructures of magnetic materials are unique platforms for studying spin-related phenomena in two dimensions (2D) and have promising applications in spintronics and magnonics. Here, we report the fabrication of 2D magnetic lateral heterostructures consisting of single-layer chromium triiodide (CrI3) and chromium diiodide (CrI2). By carefully adjusting the abundance of iodine based on molecular beam epitaxy, single-layer CrI3–CrI2 heterostructures were grown on Au(111) surfaces with nearly atomic-level seamless boundaries. Two distinct types of interfaces, i.e., zigzag and armchair interfaces, have been identified by means of scanning tunneling microscopy. Our scanning tunneling spectroscopy study combined with density functional theory calculations indicates the existence of spin-polarized ground states below and above the Fermi energy localized at the boundary. Both the armchair and zigzag interfaces exhibit semiconducting nanowire behaviors with different spatial distributions of density of states. Our work presents a novel low-dimensional magnetic system for studying spin-related physics with reduced dimensions and designing advanced spintronic devices.
