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Newly emergent type-II Weyl semimetals with topological surface states so-called Fermi arcs have attracted much attention for their novel physical properties and potential application in quantum devices. Here, we investigate the in-plane anisotropic structure and inversion symmetry breaking by angle-resolved polarized Raman and second harmonic generation and observe the anisotropic Shubnikov-de Haas effect in Weyl Semimetal MoTe2, which is only present in the b-axis (armchair chain) direction. First-principles calculation depicts the type-II Weyl points and clear topological Fermi arcs. A nontrivial π Berry's phase from Landau quantization and an extra-quantum oscillation frequency arising by Weyl orbit are obtained, which provide evidence for the existence of an anisotropic type-II Weyl state in MoTe2. This work reveals the nontrivial topological surface state of Weyl semimetal MoTe2 in both theory and experiment, providing a promising platform for unique physical properties and applications in quantum information processing. [ABSTRACT FROM AUTHOR]

Two-dimensional (2D) magnetic materials have aroused tremendous interest due to the 2D confinement of magnetism and potential applications in spintronic and valleytronic devices. However, most of the currently 2D magnetic materials are achieved by the exfoliation from their bulks, of which the thickness and domain size are difficult to control, limiting the practical device applications. Here, we demonstrate the realization of thickness-tunable rhombohedral Cr2Se3 nanosheets on different substrates via the chemical vapor deposition route. The magnetic transition temperature at about 75 K is observed. Furthermore, van der Waals heterostructures consisting of Cr2Se3 nanosheets and monolayer WS2 are constructed. We observe the magnetic proximity effect in the heterostructures, which manifests the manipulation of the valley polarization in monolayer WS2. Our work contributes to the vapor growth and applications of 2D magnetic materials. [ABSTRACT FROM AUTHOR]

Doping can change the intrinsic properties of 2D materials by tuning their electronic structure. In this work, high‐quality 2D In‐doped SnS2 (In‐SnS2) monolayer is reported through chemical vapor transport method and following mechanical cleavage process. The In content of In‐SnS2 is ≈0.9%, and doping results in the downward shift of the Fermi level compared with the undoped one. Transmission electron microscopy images show that doping is uniform in the In‐SnS2 nanosheets with high quality. The In‐SnS2 monolayer field effect transistors (FETs) show p‐type feature which is different from the n‐type feature of undoped SnS2. The average hole produced by one In atom is estimated as 0.37 from FETs measurement. Density functional theory calculations show that the decreasing of hole concentration results from the hole killing mechanism induced by S vacancy. The results suggest that changing the polarity of 2D semiconductor by doping is successful, and In‐SnS2 monolayer has great potential in the applications of electronics and optoelectronics. [ABSTRACT FROM AUTHOR]

Newly emergent type-II Weyl semimetals with topological surface states so-called Fermi arcs have attracted much attention for their novel physical properties and potential application in quantum devices. Here, we investigate the in-plane anisotropic structure and inversion symmetry breaking by angle-resolved polarized Raman and second harmonic generation and observe the anisotropic Shubnikov-de Haas effect in Weyl Semimetal MoTe2, which is only present in the b-axis (armchair chain) direction. First-principles calculation depicts the type-II Weyl points and clear topological Fermi arcs. A nontrivial π Berry's phase from Landau quantization and an extra-quantum oscillation frequency arising by Weyl orbit are obtained, which provide evidence for the existence of an anisotropic type-II Weyl state in MoTe2. This work reveals the nontrivial topological surface state of Weyl semimetal MoTe2 in both theory and experiment, providing a promising platform for unique physical properties and applications in quantum information processing. [ABSTRACT FROM AUTHOR]