Antiferromagnetic (AF) materials are attracting increasing interest for research in magnetic physics and spintronics. Here, we report a controllable synthesis of room-temperature AF α-MnTe nanocrystals (Néel temperature ∼307 K) via the molten-salt-assisted chemical vapor deposition method. The growth kinetics are investigated regarding the dependence of flake dimension and macroscopic shape on growth time and temperature. The high crystalline quality and atomic structure are confirmed by various crystallographic characterization means. Cryogenic magneto-transport measurements reveal anisotropic magnetoresistance (MR) response and complicated dependence of MR on temperature, owing to the subtle competition among multiple scattering mechanisms of thermally excited magnetic disorders (magnon drag), magnetic transition, and thermally populated lattice phonons. Overall positive MR behavior with two transitions in magnitude is observed when out-of-plane external magnetic field (B) is applied, while a transition from negative to positive MR response is recorded when in-plane B is applied. The rich magnetic transport properties render α-MnTe a promising material for exploiting functional components in magnetic devices.

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Molybdenum dioxide (MoO 2) a kind of semi-metal material shows many unique properties, such as high melting point, good thermal stability, large surface area-to-volume ratio, high-density surface unsaturated atoms, and excellent conductivity. There is a strong connection between structural type and optoelectronic properties of 2D nanosheet. Herein, the rectangular and hexagonal types of thin and thick MoO 2 2D nanosheets were successfully prepared from MoO 3 powder using two-zone chemical vapor deposition (CVD) with changing the experimental parameters, and these fabricated nanosheets displayed different colors under bright-field microscope, possess margins and smooth surface. The thickness of the blue hexagonal and rectangular MoO 2 nanosheets are~25 nm and~30 nm, respectively, while typical thickness of orange-colored nanosheet is around~100 nm. Comparative analysis and investigations were carried out, and mix-crystal phases were indentified in thick MoO 2 as main matrix through Raman spectroscopy. For the first time, the emission bands obtained in thick MoO 2 nanosheets via a Cathodoluminescence (CL) system exhibiting special properties of semi-metallic and semiconductors ; however, no CL emission detected in case of thin nanosheets. The electrical properties of thin MoO 2 nanosheets with different morphologies were compared, and both of them demonstrated varying metallic properties. The resistance of thin rectangular nanosheet was~25 Ω at ± 0.05 V while 64 Ω at ± 0.05 V was reported for hexagonal nanosheet, and observed lesser resistance by rectangular nanosheet than hexagonal nanosheet.

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