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Magnetic topological insulators (MTIs) offer a combination of topologically nontrivial characteristics and magnetic order and show promise in terms of potentially interesting physical phenomena such as the quantum anomalous Hall (QAH) effect and topological axion insulating states. However, the understanding of their properties and potential applications have been limited due to a lack of suitable candidates for MTIs. Here, we grow two-dimensional single crystals of Mn(SbxBi(1-x))2Te4 bulk and exfoliate them into thin flakes in order to search for intrinsic MTIs. We perform angle-resolved photoemission spectroscopy, low-temperature transport measurements, and first-principles calculations to investigate the band structure, transport properties, and magnetism of this family of materials, as well as the evolution of their topological properties. We find that there exists an optimized MTI zone in the Mn(SbxBi(1-x))2Te4 phase diagram, which could possibly host a high-temperature QAH phase, offering a promising avenue for new device applications.

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Ulcers are a lower-extremity complication of diabetes with high recurrence rates. Oxidative stress has been identified as a key factor in impaired diabetic wound healing. Hyperglycemia induces an accumulation of intracellular reactive oxygen species (ROS) and advanced glycation end products, activation of intracellular metabolic pathways, such as the polyol pathway, and PKC signaling leading to suppression of antioxidant enzymes and compounds. Excessive and uncontrolled oxidative stress impairs the function of cells involved in the wound healing process, resulting in chronic non-healing wounds. Given the central role of oxidative stress in the pathology of diabetic ulcers, we performed a comprehensive review on the mechanism of oxidative stress in diabetic wound healing, focusing on the progress of antioxidant therapeutics. We summarize the antioxidant therapies proposed in the past 5 years for use in diabetic wound healing, including Nrf2- and NFκB-pathway-related antioxidant therapy, vitamins, enzymes, hormones, medicinal plants, and biological materials.

The enhancement of terahertz (THz) radiation is of extreme significance for the realization of the THz probe and imaging. However, present THz technologies are far from being enough to realize high-performance and room-temperature THz sources. Fortunately, topological insulators (TIs), with spin-momentum-locked Dirac surface states, are expected to exhibit a high terahertz emission efficiency. In this work, the novel concept of a Rashba-state-enhanced spintronic THz emitter is demonstrated on the basis of ferromagnet/heavy metal/topological insulator (FM/HM/TI) heterostructure. We find that the THz emission intensity changes as a function of HM interlayer thickness, and a 1.98 times higher intensity compared to that of FM/TI can be achieved when a meticulously designed thickness of the HM layer is inserted. The improvement of terahertz radiation is ascribed to the additive effect of Rashba splitting and topological surface states at the HM/TI interface. These results offer new possibilities for realizing spintronic THz emitters in TI-based magnetic heterostructures.

The WSe2 monolayer in 1T’ phase is reported to be a large‐gap quantum spin Hall insulator, but is thermodynamically metastable and so far the fabricated samples have always been in the mixed phase of 1T’ and 2H, which has become a bottleneck for further exploration and potential applications of the nontrivial topological properties. Based on first‐principle calculations in this work, it is found that the 1T’ phase could be more stable than 2H phase with enhanced interface interactions. Inspired by this discovery, SrTiO3 (100) is chosen as substrate and WSe2 monolayer is successfully grown in a 100% single 1T’ phase using the molecular beam epitaxial method. Combining in situ scanning tunneling microscopy and angle‐resolved photoemission spectroscopy measurements, it is found that the in‐plane compressive strain in the interface drives the 1T'‐WSe2 into a semimetallic phase. Besides providing a new material platform for topological states, the results show that the interface interaction is a new approach to control both the structure phase stability and the topological band structures of transition metal dichalcogenides.

Two-dimensional (2D) transition metal dichalcogenides MX 2 (M = Mo, W, X = S, Se, Te) attracts enormous research interests in recent years. Its 2H phase possesses an indirect to direct bandgap transition in 2D limit, and thus shows great application potentials in optoelectronic devices. The 1T′ crystalline phase transition can drive the monolayer MX 2 to be a 2D topological insulator. Here we realized the molecular beam epitaxial (MBE) growth of both the 1T′ and 2H phase monolayer WSe 2 on bilayer graphene (BLG) substrate. The crystalline structures of these two phases were characterized using scanning tunneling microscopy. The monolayer 1T′-WSe 2 was found to be metastable, and can transform into 2H phase under post-annealing procedure. The phase transition temperature of 1T′-WSe 2 grown on BLG is lower than that of 1T′ phase grown on 2H-WSe 2 layers. This thermo-driven crystalline phase transition makes the monolayer WSe 2 to be an ideal platform for the controlling of topological phase transitions in 2D materials family.

The scattering process induced by impurities in graphene plays a key role in transport properties. Especially, the disorder impurities can drive the ordered state with a hexagonal superlattice on graphene by electron-mediated interaction at a transition temperature. Using angle-resolved photoemission spectroscopy (ARPES), we reveal that the epitaxial monolayer and bilayer graphene with various impurities display global elastic intervalley scattering and quantum interference below the critical temperature (34 K), which leads to a set of new folded Dirac cones at the Brillouin-zone center by mixing two inequivalent Dirac cones. The Dirac electrons generated from intervalley scattering without chirality can be due to the breaking of the sublattice symmetry. In addition, the temperature-dependent ARPES measurements indicate the thermal damping of quantum interference patterns from Dirac electron scattering on impurities. Our results demonstrate that the electron scattering and interference induced by impurities can completely modulate the Dirac bands of graphene.