Jinghao Deng#, Deping Guo#, Yao Wen, Shuangzan Lu, Zhengbo Cheng, Zemin Pan, Tao Jian, Yusong Bai, Hui Zhang, Wei Ji*, Jun He*, Chendong Zhang*
Abstract:
Multiferroicity allows magnetism to be controlled using electric fields or vice versa, which has gained tremendous interest in both fundamental research and device applications. A reduced dimensionality of multiferroic materials is highly desired for device miniaturization, but the coexistence of ferroelectricity and magnetism at the two-dimensional limit is still debated. Here, we used a NbSe2 substrate to break both the C3 rotational and inversion symmetries in monolayer VCl3 and thus introduced exceptional in-plane ferroelectricity into a two dimensional magnet. Scanning tunnelling spectroscopy directly visualized ferroelectric domains and manipulated their domain boundaries in monolayer VCl3, where coexisting antiferromagnetic order with canted magnetic moments was verified by vibrating sample magnetometer measurements. Our density functional theory calculations highlight the crucial role that highly directional interfacial Cl–Se interactions play in breaking the symmetries and thus in introducing in-plane ferroelectricity, which was further verified by examining an ML-VCl3/graphene sample. Our work demonstrates an approach to manipulate the ferroelectric states in monolayered magnets through van der Waals interfacial interactions.
Fig. 1. Morphology and atomic structure of ML-VCl3 on a NbSe2 substrate.
Fig. 2. IP electric polarizations characterized by band bending near DWs.
Fig. 3. Experimental and theoretical investigations of the magnetic order in epitaxy ML-VCl3.
Fig. 4. Anisotropic charge transfer–induced IP ferroelectricity and comparison with the VCl3-graphene interface.
近日，中国人民大学物理学院季威教授研究组联合武汉大学张晨栋教授等组成联合研究团队，通过理论计算结合实验测量，在单层二维材料三氯化钒（VCl3）中，实现了反铁磁性与铁电性共存，揭示了范德华界面相互作用对磁-电共存的调控机制。相关研究成果以“Evidence of Ferroelectricity in an Antiferromagnetic Vanadium Trichloride Monolayer”为题，于2025年3月5日发表《Science》子刊《Science Advances》[Science Advances 11, eado6538 (2025)]上。
The newly-discovered chromium-based kagome metal CsCr3Sb5 has garnered significant interest due to its strong electron correlations, intertwined orders and potential for unconventional superconductivity under high pressure. However, the nature of superconducting and magnetic interactions during the transition from the parent compound CsV3Sb5 to CsCr3Sb5 remains elusive. Here, we report the discovery of spatially anisotropic Kondo resonance which intertwines with the superconducting gap, facilitated by the introduction of magnetic Cr impurities into the kagome superconductor CsV3Sb5. In addition to the gradual suppression of long-ranged charge-density-wave orders, dilute Cr dopants induce local magnetic moments, giving rise to the emergence of Kondo resonances. In addition, the Kondo resonance forms spatially anisotropic ripple-like structures around the Cr dopants, breaking all local mirror symmetries. This anisotropy arises from the antiferromagnetic coupling between itinerant electrons and the Cr-induced spin-up electrons. Remarkably, as the Kondo screening develops, the coherence peak and depth of superconducting gap with finite zero-energy conductance significantly enhances. It indicates that non-superconducting pairs at the Fermi surface in the parent compound participate in the Kondo effect, effectively screening the magnetic moments of Cr dopants while simultaneously enhancing the superfluid density. Our findings pave a unique pathway for exploring the interplay between superconductivity and local magnetic moments in kagome systems.
Peng-Jie Guo, Xiao-Yao Hou, Ze-Feng Gao, Huan-Cheng Yang, Wei Ji, Zhong-Yi Lu
Abstract:
Altermagnetic materials, with real-space antiferromagnetic arrangement and reciprocal-space anisotropic spin splitting, have attracted much attention. However, the spin splitting is small in most altermagnetic materials, which is a disadvantage to their application in electronic devices. In this study, based on symmetry analysis and the first-principles electronic structure calculations, we predict for the first time two Luttinger compensated bipolarized magnetic semiconductors Mn(CN)2 and Co(CN)2 with isotropic spin splitting as in the ferromagnetic materials. Our further analysis shows that the Luttinger compensated magnetism here depends not only on spin group symmetry, but also on the crystal field splitting and the number of d-orbital electrons. In addition, the polarized charge density indicates that both Mn(CN)2 and Co(CN)2 have the quasi-symmetry T{\tau} , resulting from the crystal field splitting and the number of d-orbital electrons. The Luttinger compensated magnetism not only has the zero total magnetic moment as the antiferromagnetism, but also has the isotropic spin splitting as the ferromagnetism, thus our work not only provides theoretical guidance for searching Luttinger compensated magnetic materials with distinctive properties, but also provides a material basis for the application in spintronic devices.
Xiaoqing Chen#, Huijuan Zhao#, Ruixiang Fei, Chun Huang, Jingsi Qiao, Cheng Sun, Haiming Zhu, Li Zhan, Zehua Hu, Songlin Li, Li Yang, Zemin Tang, Lianhui Wang, Yi Shi, Wei Ji, Jian-Bin Xu, Li Gao*, Xuetao Gan* & Xinran Wang*
Abstract:
Two-dimensional materials offer strong light-matter interaction and design flexibility beyond conventional bulk semiconductors, but an intrinsic limit is the low absorption imposed by the atomic thickness. A long-sought-after goal is to achieve complementary absorption enhancement through energy transfer (ET) to break this intrinsic limit. However, it is found challenging due to the competing charge transfer process and lack of resonance in exciton states. Here, we report highly efficient energy transfer (ET) in a 2D hybrid organic-inorganic heterostructure (HOIST) of Me-PTCDI/WS2. Resonant ET is observed leading to enhanced WS2 PL by as much as 124 times. We identify Dexter exchange between the Frenkel state in donor and an excited 2s state in acceptor as the main ET mechanism, as supported by density functional theory calculations. We further demonstrate ET-enhanced phototransistor devices with enhanced responsivity by nearly 1000 times without sacrificing the response time. Our results expand the understanding of inter-layer relaxation.
