Breathing kagome materials Nb3X8 (X = F, Cl, Br, I) have attracted broad interest owing to their Mott insulating behavior and stacking-dependent magnetic ground states. However, the role of interlayer coupling in modulating these properties remains underexplored. Here, using density functional theory with Hubbard U corrections, we systematically investigated how interlayer coupling affects the Mott insulating states and magnetic ground states across 24 bilayer stacking configurations for each compound. We found that all bilayers remain Mott insulators, demonstrating robust Mottness. Driven by the competition between interlayer Pauli repulsion and hopping, most stackings favor interlayer AFM order, including conventional and compensated AFM, while some exhibit AFM-FM degeneracy or stabilize interlayer FM. This robustness of Mott states coexisting with tunable interlayer magnetism provides novel analysis and insights for research on breathing kagome Mott insulators.
Deping Guo*, Weihan Zhang, Canbo Zong, Cong Wang, Wei Ji
Abstract:
Luttinger compensated antiferromagnets (LcAFMs), combining spin polarization with vanishing net magnetization, offer distinct advantages for next-generation spintronic applications. Using first-principles calculations, we demonstrate that conventional antiferromagnetic CrCl2 double chains can be transformed into one-dimensional LcAFMs under an external electric field, exhibiting pronounced isotropic spin splitting. The magnitude of the splitting, as well as the bandgap, can be effectively tuned by both in-plane and out-of-plane fields, thereby providing greater controllability than in two-dimensional counterparts. To further enhance the tunability, we design a nearly lattice-matched CrCl2/MoTe2 heterostructure and uncover that interfacial charge transfer generates a built-in electric field, inducing spin splitting comparable to that driven by external fields. These results establish interfacial engineering as a highly efficient route to realize and manipulate LcAFM states in low-dimensional magnets, expanding the design principles for spintronic functionalities at the nanoscale.
Deju Zhang, Zhe Wang, Sihang Che, Wei Ji, and Yanning Zhang*
Abstract:
In the field of low-energy-consumption applications, electrical control of magnetism has attracted considerable research attention. Here, we report that the Janus Cr2S2Se monolayer, where Se atoms substitute the upper S layer in the Cr2S3 monolayer, is structural stable. We find that the Janus Cr2S2Se monolayer favors the ferromagnetic configuration with a high Curie temperature of 279 K, and shows semiconducting characteristics with an indirect band gap of 0.44 eV and a valley splitting of 33 meV. By constructing a van der Waals multiferroic heterostructure combined with α-In2Se3 monolayer, its interlayer magnetism can be switched between two types of magnetic coupling via nonvolatile manipulation of the ferroelectric polarization. Our study reveals the switchable magnetism of the Janus Cr2S2Se monolayer, making it promising candidates for use in next-generation low-dimensional spintronics applications.
Kuakua Lu#, Yun Li#,*, Qijing Wang#,* Linlu Wu#, Xinglong Ren, Xu Chen, Luhao Liu, Yating Li, Xiaoming Xu, Qingkai Zhang, Di Wang, Liqi Zhou, Mingfei Xiao, Sai Jiang, Mengjiao Pei, Haoxin Gong, William Wood, Ian E. Jacobs, Junzhan Wang, Gang Chen, Peng Wang, Zhaosheng Li, Chunfeng Zhang, Xinran Wang, Xu Wu, Yeliang Wang, Wei Ji, Songlin Li, Jingsi Qiao*, Yi Shi*, Henning Sirringhaus*
Abstract:
Metallic charge transport of field-induced carriers can be observed in single-crystal silicon over a wide temperature range. Such behaviour is rare in undoped organic semiconductors but is beneficial for engineering devices with advanced performance. Here we report metallic charge transport in conjugated molecular bilayers down to 8 K with an electrical conductivity of up to 245 S cm−1 and a Hall mobility larger than 100 cm2 V−1 s−1 at 20 K. We use molecular-crystal bilayers of the organic semiconductor 2-decyl-7-phenyl-[1]benzothieno[3,2-b][1]benzothiophene. We infer that this transport behaviour originates from the phenyl bridge coupling between the two molecular layers, which suppresses molecular vibrations and weakens Coulomb interactions. We develop a controlled method for introducing defects, using which we observe a disorder-driven metal–insulator transition in the molecular crystal.
Yanyan Geng (耿燕燕)†, Manyu Wang (王曼雨)†, Shumin Meng (孟淑敏), Shuo Mi (米烁), Chang Li (李畅), Huiji Hu (胡会吉), Jianfeng Guo (郭剑锋), Rui Xu (许瑞), Fei Pang (庞斐), Wei Ji (季威), Weichang Zhou (周伟昌)* and Zhihai Cheng (程志海)*
Abstract:
Transition-metal dichalcogenides hosting multiple competing structural and electronic phases are thus ideal platforms for constructing polytype heterostructures with emergent quantum properties. However, controlling phase transitions to form diverse heterostructures inside a single crystal remains challenging. In this study, we realize vertical/lateral polytype heterostructures in a hole-doped Mott insulator via thermal annealing-induced structural transitions. Raman spectroscopy, atomic force microscopy and scanning Kelvin probe force microscopy confirm the coexistence of T-H polytype heterostructures. Atomic-scale scanning tunneling microscopy / spectroscopy measurements reveal the transparent effect in 1H/1T vertical heterostructures, where positive bias v oltage induces in a pronounced superposition of the sqrt13 × sqrt13 CDW of the 1T-layer on the 1H-layer. By systematically comparing the 1T/1H and 1T/1T interfaces, we demonstrate that the metallic 1H-layer induces a Coulomb screening effect on the 1T-layer, suppressing the formation of CDW domain walls and forming more ordered electronic states. These results clarify the interfacial coupling between distinct quantum many-body phases and establish a controllable pathway for constructing two-dimensional polytype heterostructures with tunable electronic properties.
