Anisotropy in crystals arises from different lattice periodicity along different crystallographic directions, and is usually more pronounced in two dimensional (2D) materials. Indeed, in the emerging 2D materials, electrical anisotropy has been one of the recent research focuses. However, key understandings of the in-plane anisotropic resistance in low-symmetry 2D materials, as well as demonstrations of model devices taking advantage of it, have proven difficult. Here, we show that, in few-layered semiconducting GaTe, electrical conductivity anisotropy between x and y directions of the 2D crystal can be gate tuned from several fold to over 10 3 . This effect is further demonstrated to yield an anisotropic non-volatile memory behavior in ultra-thin GaTe, when equipped with an architecture of van der Waals floating gate. Our findings of gate-tunable giant anisotropic resistance effect pave the way for potential applications in nanoelectronics such as multifunctional directional memories in the 2D limit.

Thermal barrier coatings (TBCs) play a vitally important role in protecting the hot parts of a gas turbine from high temperature and corrosion effectively. More and more attention has been paid to the performance modification of ZrO2-based ceramics and seeking for new ceramic materials to meet requirements of gas turbine TBCs. The working principle, merits, and demerits of main technologies for coating preparation are elaborated in this paper, and the properties of new ceramic materials are reviewed. It is found that the thermal conductivity, thermal stability, mechanical properties, and other performances of traditional ZrO2-based ceramics could be improved effectively by doping modification. The emphases for new ceramic materials research were put on pyrochlores, magnetoplumbites, rare-earth tantalates, etc. Rare-earth tantalates with great potentials as new top ceramic materials were described in detail. In the end, the development directions of advanced top ceramic coatings, combining doping modification with preparation technology to regulate and control structure property of high-performance ceramic material, were put forward.

Low-temperature synthesis of β-FeSe superconductor from soluble precursors is a great challenge in the chemical solution approaches. Here, we develop a new and facile solution-based synthetic route to first fabricate narrow-phased β-FeSe superconductor with soluble iron and selenium sources as starting materials. The growth mechanism of β-FeSe superconductors is discussed by kinetically controllable syntheses in various reaction conditions. Chemically engineering the stoichiometry of β-FeSe products by selenium-diffusion process gives rise to a transition of antiferromagnetic-superconducting-antiferromagnetic (AFM-SC-AFM) order. Once the AFM order is suppressed, SC β-FeSe nanosheets show a tunable initial superconducting transition temperature (T C ) from 3.2 to 10 K in the superconducting regime. Electrical measurements on superconducting β-FeSe exhibit an upper critical magnetic field higher than 14 T, showing potential application of β-FeSe nanosheet for superconducting device. This method provides guidance for future applications in such chemical solutions for diffusioncontrolled synthesis of narrow-phased functional materials, which are enriched of abundant fundamental physics and potentials for future applications.