A family of $M{A}_2{Z}_4$ materials has recently inspired great interest due to its exotic geometry and intriguing electronic properties. Here we investigate the electronic transport and photoelectric properties of ${\mathrm{Mo}\mathrm{Si}}_2{\mathrm{P}}_4$ monolayer (MSP ML) that has a small direct gap using first-principles calculations. We design several model nanodevices based on MSP ML, including p-n junction diodes, p-i-n junction field-effect transistors, and photoelectric transistors. We demonstrate that these MSP-ML-based nanodevices yield superb transport properties, including significant rectifying effect, high electrical anisotropy, pronounced field-effect behavior, strong photoelectric response, and large photovoltaic power. These findings reveal the multifunctional nature of ${\mathrm{Mo}\mathrm{Si}}_2{\mathrm{P}}_4$ monolayer, promising its application as a designer material in next-generation ultrathin flexible semiconductor nanodevices.

A van der Waals (vdW) heterostructure is formed by combining multiple materials through vdW bonds. It can combine the advantages of electronic, optical, thermal, and magnetic properties of different 2D materials and has the potential to develop into the next generation of high‐performance functional devices. Herein, the current research advances of vdW heterostructures are reviewed. First, current fabrication methods and physical structures of vdW heterostructures are summarized. The 2D/nD (n = 0,1,2,3) mixed‐dimensional heterostructures are discussed in detail. Second, a new type of vdW heterostructure is introduced based on two‐dimensional electron gas with a nanoscale junction interface. Finally, the application prospects of vdW heterostructures in photoelectric and memory devices are further outlined by combing new applications in the neural networks. This review shows that vdW heterostructures have great advantages in high integration, energy harvesting, and logical operations, and it provides directions and suggestions for the future research and application of environmentally friendly, high‐performance, and smart functional devices.

The population of surface-trapped electrons determines the SERS performance of a W₁₈O₄₉ substrate, as proved by construction of metal–semiconductor or organic–semiconductor interfaces.

The two-dimensional intrinsic ferromagnet $\mathrm{Cr}\mathrm{S}\mathrm{Cl}$ monolayer has considerable potential for application in the development of spintronic devices because of properties such as robust ferromagnetic ordering, large spin polarization, high Curie temperature, and high carrier mobilities. Here, we investigate the electromagnetic properties of the $\mathrm{Cr}\mathrm{S}\mathrm{Cl}$ monolayer and the spin-transport properties of some conceptual magnetic devices we construct, such as p-n-junction diodes, field-effect transistors, and phototransistors, by means of first-principles calculations. The results indicate that the p-n-junction diodes of the $\mathrm{Cr}\mathrm{S}\mathrm{Cl}$ monolayer exhibit full spin-polarized transport behavior, and both the p-n and p-i-n junctions show excellent spin-filtering behavior. The phototransistor of the $\mathrm{Cr}\mathrm{S}\mathrm{Cl}$ monolayer exhibits spin-resolved photoresponse characteristics for different wavelengths of light. Furthermore, it possesses the ability to generate a fully spin-up polarized current in the visible range. Our results provide key insights into the fundamental physical properties and the underlying transport and photoresponse mechanisms of the $\mathrm{Cr}\mathrm{S}\mathrm{Cl}$ monolayer.

Materials hosting intrinsic room-temperature ferromagnetism have significant application in spintronics. In this context, the transition metal sulfide chromium telluride (${\mathrm{Cr}}_x{\mathrm{Te}}_y$) has sparked significant attention due to its room-temperature ferromagnetism, as well as high magnetic anisotropy, easy tunability, and air stability. This study carefully examines the magnetic characteristics of an intrinsic room-temperature ferromagnetic ${\mathrm{Cr}}_3{\mathrm{Te}}_4$ single crystal. Magnetization measurements identify a paramagnetic-to-ferromagnetic (PM-FM) phase transition at $T_C\sim 322$ K and high magnetic anisotropy. Meanwhile, a coexistence of ferromagnetism and antiferromagnetism is unveiled below $T_N\sim 90$ K. A systematic investigation of magnetization isotherms collected near $T_C$ provides the asymptotic critical exponents $\beta =0.365\left(5\right), \gamma =1.212\left(9\right), \delta =4.580\left(4\right)$ for $H//ab$, and $\beta =0.370\left(3\right), \gamma =1.329\left(1\right), \delta =4.554\left(9\right)$ for $H//c$. The obtained critical exponents for $H//ab$ and $H//c$ suggest strong anisotropic and multiple magnetic interactions in ${\mathrm{Cr}}_3{\mathrm{Te}}_4$. The comprehensive $H-T$ phase diagrams for $H//ab$ and $H//c$ are constructed using universal scaling and detailed magnetization, revealing strong field-dependent anisotropic room-temperature ferromagnetism and coexistence of ferromagnetism, antiferromagnetism, and noncollinear ferromagnetism. The multiple phases demonstrate that the magnetic couplings in ${\mathrm{Cr}}_3{\mathrm{Te}}_4$ are mediated by intralayer super exchange, interlayer double exchange, and direct exchange.