Spin-gapless van der Waals heterostructure for spin gating through magnetic injection devices.

Spin-gapless semiconductors (SGSs) are new magnetic zero-bandgap materials whose band structure is extremely sensitive to external influences (pressure or magnetic fields) and have great potential for high-speed and low-energy spintronics applications. The first-principles method was used to systematically study the heterostructures constructed of an asymmetric surface-functionalized Janus MXene material, Cr2NOF, and a two-dimensional hexagonal lattice (2DH) semiconductor material and to study the effects of the electronic structure, Curie temperature, magnetism, and the design of unusual band structures and magnetic injection in the bilayer to obtain an SGS structure. Through the design and construction of Cr2NOF/2DH van der Waals heterojunction spintronic devices, the spin-filtering effect of the devices can reach 100%, especially, realizing spin gating through magnetic injection. We report the transport mechanism of the heterojunction spintronic devices to achieve the goal of a controllable optimization of the device functions, which provides a theoretical basis for the design of MXene van der Waals heterojunctions for high-efficiency and low-power-consumption spintronic devices.

A first-principles study of the ultra-high spin rectification effect based on nitride MXenes (Sc2NO2, Ti2NO2).

Nitride MXenes exhibit inherent strong chemical stability and ferromagnetic properties, which are significant for their application in nanoscale spintronic devices. To demonstrate the potential of nitride MXenes in spintronics, we have designed a Sc2NO2/Ti2NO2 heterojunction and investigated its spin transport properties using first principles calculations combined with the non-equilibrium Green's function. The results show that the Sc2NO2/Ti2NO2 heterojunction has a stable negative differential resistance effect and a great spin rectification effect with a rectification ratio of 1.73 × 1011. The corresponding energy band structures and the transport behavior establish the mechanism for such properties. In addition, the perfect two-dimensional morphology provides a suitable nanostructured material for developing spintronic devices.

Potential outstanding physical properties of novel black arsenic phosphorus As0.25P0.75/As0.75P0.25 phases: a first-principles investigation.

Black arsenic phosphorus As0.5P0.5 has been studied as an excellent candidate for electronic and optoelectronic applications. At the same time, the physical properties of As x P1-x alloys with other compositions were not investigated. In this work, we design seven As0.25P0.75(P-I and P-II)/As0.75P0.25(As-(I, II, III, IV and V)) phases with molecular dynamics stability. First principles calculations are used to study their electronic structures under strain as well as their carrier mobilities. By calculating Perdew-Burke-Ernzerhof (PBE) electronic bands, we reveal that these materials are direct-gap semiconductors similar to black phosphorus except for the As-IV phase. It is also found that the carrier mobility in the P-I and As-V phases can reach 104 cm2 V-1 s-1. The electronic structures of the P-I, As-IV and As-V phases under strain are studied. Finally, we design caloritronic devices based on armchair and zigzag nanoribbons. The value of the Seebeck coefficient of the armchair and zigzag devices made from the P-II phases are found to be as high as 2507 and 2005 µW K-1 at 300 K. The thermal properties of the arsenic phosphorus phases under consideration are further studied by calculating their thermoelectric figure of merit, ZT values. These values are as high as 10.88 for the armchair devices based on the As-III phase and 4.59 for the zigzag devices based on the As-V phase at room temperature, and 15 and 7.16 at 600 K, respectively. The obtained results demonstrate that the As0.25P0.75/As0.75P0.25 phases studied here can be regarded as potential candidates for thermoelectric and electronic device applications.

Bimetallic Alloys b-AsxP1-x at High Concentration Differences: Ideal for Photonic Devices.

Black arsenic phosphorus (b-AsxP1-x) is expected to be one of the primary materials for future photonic devices. However, the x-factor is randomly estimated and applied in photonic devices in current studies, rather than systematically analyzing it for a comprehensive understanding. Herein, AsxP1-x switches from a direct band gap semiconductor to an indirect band gap one at x = 0.75. AsxP1-x at x ≤ 0.25 is capable of broadband absorption, while b-AsxP1-x at x ≥ 0.75 can only absorb at specific wavelengths in the perspective of the electron energy transition. Additionally, the optoelectronic response of the integral field-effect transistor configurations constructed with b-AsxP1-x is investigated systematically as a photodetector device. The photonic response characteristics show high polarization sensitivity at x ≥ 0.75, but a typical circuit system signal at x ≤ 0.25. These results suggest that b-AsxP1-x with high concentration differences is a perfect candidate for photonic material.