Interlayer coupling driven rotation of the magnetic easy axis in MnS⁢e2 monolayers and bilayers

Interlayer coupling driven rotation of the magnetic easy axis in MnS⁢e2 monolayers and bilayers

Zhongqin Zhang, Cong Wang†,*, PengJie Guo, Linwei Zhou, Yuhao Pan, Zhixin Hu*, and Wei Ji*

Interlayer coupling plays a critical role in tuning the electronic structures and magnetic ground states of two-dimensional materials, influenced by the number of layers, interlayer distance, and stacking order. However, its effect on the orientation of the magnetic easy axis remains underexplored. In this study, we demonstrate that interlayer coupling can significantly alter the magnetic easy-axis orientation, as shown by the magnetic easy-axis of monolayer 1T-MnSe2 tilting 33° from the z-axis, while aligning with the z-axis in the bilayer. This change results from variations in orbital occupations near the Fermi level, particularly involving nonmetallic Se atoms. Contrary to the traditional focus on magnetic metal atoms, our findings reveal that Se orbitals play a key role in influencing the easy-axis orientation and topological Chern numbers. Furthermore, we show that the occupation of Se p-orbitals, and consequently the magnetic anisotropy, can be modulated by factors such as stacking order, charge doping, and external strain. Our results highlight the pivotal role of interlayer coupling in tuning the magnetic properties of layered materials, with important implications for spintronic applications.

Altermagnetism in parallel-assembled single-atomic magnetic chains

Altermagnetism in parallel-assembled single-atomic magnetic chains

Deping Guo#, Canbo Zong#, Cong Wang, Weihan Zhang, and Wei Ji*

Altermagnetism has recently attracted significant interest in three- and two-dimensional materials, yet its realization in quasi-one-dimensional (Q1D) materials remains largely unexplored due to stringent symmetry constraints. Here, we systematically investigated the emergence of altermagnetism in 30 Q1D monolayer prototypes, self-assembled from intra-chain anti-ferrimagnetically coupled XYn single-atomic magnetic chains, using symmetry analysis and high-throughput density functional theory calculations. Symmetry analysis identifies four structural prototypes capable of hosting altermagnetism, which expand to 192 monolayers upon materialization. Our calculations further reveal eight dynamically stable Q1D altermagnets, all belonging the AA-stacked intra-chain AFM coupled β-XY₃ prototype, exhibiting d-wave-like spin splitting. Furthermore, we demonstrate the tunability of altermagnetic properties by varying inter-chain spacing and applying external electric fields. By optimizing these parameters, altermagnetism can be significantly enhanced, with spin splitting reaching several hundred meV in CoTe3, or substantially suppressed, leading to a transition to a nodal-line semiconducting state in CrCl3. These findings establish a diverse and highly tunable family of Q1D altermagnetic candidate materials.

Controllable Synthesis of Submillimeter Ultrathin 2D Ferromagnetic Cr5Te8 Nanosheets by GaTe-Assisted CVD

Controllable Synthesis of Submillimeter Ultrathin 2D Ferromagnetic Cr5Te8 Nanosheets by GaTe-Assisted CVD

Hanxiang Wu, Jianfeng Guo, Hua Xu, Zhaxi Suonan, Shuo Mi, Le Wang, Shanshan Chen, Rui Xu, Wei Ji, Zhihai Cheng, and Fei Pang*

2D non-van der Waals (vdW) Cr5Te8 has attracted widespread research interest for its air stability and thickness-dependent magnetic properties. However, the growth of large-scale ultrathin 2D Cr5Te8 remains challenging. Here, we selected GaTe powder as precursor to supply Te monomers and fabricated submillimeter 2D Cr5Te8 nanosheets. By optimizing the growth temperature and source–substrate distance (DSS), we successfully achieved Cr5Te8 nanosheets with lateral sizes of up to ~0.19 mm and corresponding thicknesses down to ~4.8 nm. The role of GaTe enhances the efficient Te atoms concentration, which promoted the lateral growth of Cr5Te8 nanosheets. Furthermore, our findings reveal the presence of Cr5Te8 nanosheets exhibiting serrated edges and a stacked structure like wedding cakes. Magnetic property measurement revealed the intense out-of-plane ferromagnetism in Cr5Te8, with the Curie temperature (TC) of 172 K. This work paves a way for the controllable growth of the submillimeter ultrathin 2D ferromagnetic crystalline and lays the foundation for the future synthesis of millimeter ultrathin ferromagnets.

Regulated magnetic anisotropy and charge density wave in uniformly fabricated Janus CrTeSe monolayer

Regulated magnetic anisotropy and charge density wave in uniformly fabricated Janus CrTeSe monolayer

Jin-Hua Nie#, Cong Wang#, Mao-Peng Miao#, Kang-Di Niu#, Tao Xie, Ting-Fei Guo, Wen-Hao Zhang, Chao-Fei Liu, Rui-Jing Sun, Jian-Wang Zhou, Jun-Hao Lin, Wei Ji* & Ying-Shuang Fu*

Two-dimensional Janus materials exhibit unique physical properties due to broken inversional symmetries. However, it remains elusive to synthesize Janus monolayer crystals with tailored long-range magnetic orders. Here, we show a 2 ×√𝟑 charge density wave (CDW) transition and regulations of magnetization in a uniform Janus CrTeSe monolayer, selectively selenized from a pristine CrTe2 monolayer using molecular beam epitaxy. Scanning transmission electron microscopy images indicate the high quality and uniformity of the Janus structure. Spin-polarized scanning tunneling microscopy/spectroscopy measurements and density functional theory calculations unveil a robust zigzag antiferromagnetic order and the CDW transition in the CrTeSe monolayer. The one-side selenization breaks the vertical inversion symmetry, rotating the magnetic moment directions to the in-plane direction. The CDW transition opens a gap at the Fermi level and reorients the magnetic moments in tilted directions. Our work demonstrates the construction of large-area Janus structures and the tailoring of electronic and magnetic properties of two-dimensional Janus layers.

“磁性二维材料的近期研究进展”获《物理学报》2024年度最有影响论文

“磁性二维材料的近期研究进展”获《物理学报》2024年度最有影响论文

2024年10月11日,由中国物理学会主办、海南大学承办的物理学会秋季学术会议在海口举行,在第六届中国物理期刊专场报告会上,中国人民大学物理学院季威教授作为通讯作者的论文“磁性二维材料的近期研究进展”(作者:刘南舒,王聪,季威,物理学报,2022,71(12):127504 doi: 10.7498/aps.71.20220301)荣获了《物理学报》杂志颁发的“《物理学报》2024年度最有影响论文奖”。

磁性二维材料是2017年兴起的国际前沿研究领域,其材料种类丰富、物理现象新奇,也是自旋相关电子信息器件小型化的关键材料,各国争相投入大量研究资源。《磁性二维材料的近期研究进展》一文系统综述了该领域的研究进展,从磁长程序的形成机制出发,介绍了磁性二维材料的分类方式和合成手段,讨论了其磁性耦合机制、调控手段和潜在应用等。该文理论—实验并重,结合国际前沿的理论和实验结果,着重讨论了这类材料特有的磁耦合机制和调控手段。该文为初入该领域的我国青年学者提供了鲜有的、由浅入深的系统性中文文献,被多篇博士、硕士论文引用;也为一线研究人员指出了该领域面临的挑战和机遇,作为一篇中文综述已被至少18篇英文论文引用(WoS数据)。

据悉,本次奖项的评定,学会综合考虑文章的创新性,以及在Web of Knowledge 数据库的总被引频次、他引频次、施引期刊的影响力和广泛性等,经编辑部初选,正副主编审定,从《物理学报》2020—2022年发表的2708篇文章中筛选出7篇研究论文,授予“《物理学报》2024年度最有影响论文奖”。

DOI: 10.7498/aps.71.20220301