External fields effectively switch the spin channels of transition metal-doped ß-phase tellurene from first principles.

Non-volatile magnetic random-access memories have proposed the need for spin channel switching. However, this presents a challenge as each spin channel reacts differently to the external field. Tellurene is a semiconductor with a tunable bandgap, excellent stability, and high carrier concentration, but its lack of magnetic properties has hindered its application in spintronics. In this work, the influence of an external field on transition metal (TM)-doped ß-tellurene is systematically analysed from first principles. First, the active-learning moment-tensor-potential (MTP) is used to verify the thermal stability of the V-doped system with the MTP proving to be 900 times faster than the traditional method. Subsequently, under biaxial strain ranging from -2% to 10%, the V-doped system undergoes a gradual transition from a magnetic semiconductor to a spin-gapless semiconductor, and further to a half-metal and magnetic metal. The band structure can be maintained under an electric field. By examining the magnetic anisotropy energy, the lattice changes profoundly impact the electromagnetic properties, particularly with the TMs being sensitive to strain. Moreover, the band structure is reflected in the spin resolution current of the magnetic tunnel junction. This work investigates the response of doped ß-Te to external fields, revealing its potential applications in spintronics.

Highly Sensitive Broadband Polarized Photodetector Based on the As0.6P0.4/WSe2 Heterostructure toward Imaging and Optical Communication Application.

Polarization-sensitive photodetectors based on two-dimensional anisotropic materials still encounter the issues of narrow spectral coverage and low polarization sensitivity. To address these obstacles, anisotropic As0.6P0.4 with a narrow band gap has been integrated with WSe2 to construct a type-II heterostructure, realizing a high-performance polarization-sensitive photodetector with broad spectral range from 405 to 2200 nm. By operating in photovoltaic mode at zero bias, the device shows a very low dark current of ∼0.02 picoampere, high responsivity of 492 m A/W, and high photoswitching ratio of 6 × 104, yielding a high specific detectivity of 1.4 × 1012 Jones. The strong in-plane anisotropy of As0.6P0.4 endows the device with a capability of polarization-sensitive detection with a high polarization ratio of 6.85 under a bias voltage. As an image sensor and signal receiver, the device shows great potential in imaging and optical communication applications. This work develops an anisotropic vdW heterojunction to realize polarization-sensitive photodetectors with wide spectral coverage, fast response, and high sensitivity, providing a new candidate for potential applications of polarization-resolved electronics and photonics.

Multifunctional GeAs/WS2 Heterojunctions for Highly Polarization-Sensitive Photodetectors in the Short-Wave Infrared Range.

Polarization-sensitive photodetectors in the infrared range have attracted considerable attention because of their unique and wide application prospects in polarization sensors and remote sensing. However, it is challenging to achieve short-wave infrared polarization detection as most polarization-sensitive photodetectors are based on transition-metal dichalcogenide (TMD) materials with in-plane symmetric crystal structure and sizable band gap (1-2 eV). In this work, we design a type-II GeAs/WS2 heterojunction realizing superior self-driven polarization-sensitive photodetection in the short-wave infrared region. The device shows obvious rectifying behavior with a rectification ratio of 1.5 × 104 in the dark and excellent photoresponse characteristics in a broad spectral range. Accordingly, the high responsivity of 509 mA/W, large on/off ratio of 103, a high EQE of 99.8%, and a high specific detectivity of 1.08 × 1012 Jones are obtained under 635 nm laser irradiation. Taking advantage of the narrow band gap of GeAs with an anisotropic structure, the detection spectral coverage can be extended from the visible to the short-wave infrared range (635-1550 nm). Further, the GeAs/WS2 heterojunction shows high polarization sensitivity with an anisotropic photocurrent ratio of 4.5 and 3.1 at zero bias under 1310 and 1550 nm laser irradiation, respectively, which is much higher than that of reported polarization-sensitive photodetectors in the infrared region. This work provides an effective route using low-symmetry 2D materials with narrow band gap and anisotropic structure to design van der Waals (vdW) heterojunctions, realizing multifunctional optoelectronics for rectifying, photovoltaics, and polarization-sensitive photodetectors with spectral coverage up to 1550 nm.