Kagome lattices facilitate various quantum phases, yet in bulk materials, their kagome flat-bands often interact with bulk bands, suppressing kagome electronic characteristics for hosting these phases. Here, we use density-functional-theory calculations to predict the geometric and electronic structures, as well as the topological and magnetic properties, of a series of MoTe2-x kagome monolayers formed by mirror-twin-boundary (MTB) loops. We analyze nine MTB-loop configurations of varying sizes and arrangements to assess their impact on various properties. Within the intrinsic bandgap of MoTe2, we identify two sets of kagome bands, originating from in-plane and out-of-plane Te p-orbitals at MTB-loop edges and -vertices, respectively. Three configurations exhibit superior stability, while three others show comparable stability. Among these, four display bandgaps and potentially non-zero Z2 topological invariants, suggesting possible topological phases, while the remaining two are metallic and feature Stoner magnetization. These findings guide the design of kagome-based two-dimensional materials with tunable electronic, topological, and magnetic properties.
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.
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.
The integration of electronic and photonic chips hinges on the availability of efficient light sources and modulators that are compatible with on-chip interconnects. Among these, mid-infrared (mid-IR) emitters are especially critical, as they enable low-loss transmission through atmospheric windows and unlock powerful capabilities for molecular fingerprinting and chemical sensing. In this study, we demonstrate that 2D tellurium (Te) nanoflakes can serve as highly efficient, electrically tunable, and linearly polarized mid-IR emitters. Leveraging the narrow direct bandgap (≈0.36 eV) and anisotropic crystal symmetry of Te nanoflakes, we achieve electrically tunable mid-IR photoluminescence (PL) with near-complete PL intensity modulation, a stable emission wavelength (≈3.4 µm), and near-perfect linear polarization. In addition, we demonstrate a dual-gate device that allows independent control of the electrostatic doping and vertical electric field, and further theoretical analysis reveals that the electrical tunability of the PL intensity originates primarily from the gate-controlled carrier density. Building on this robust control, we demonstrate high-speed electro-optical switches and programmable logic gates for on-chip encryption, underscoring the excellent compatibility of Te with advanced optoelectronic circuits. Collectively, these advances establish Te as a cornerstone material for hybrid electronic-photonic systems, directly addressing the urgent demand for mid-IR components in next-generation optical interconnects.
