Robust and Efficient Electrical Injection of Spin-Polarized Carriers from a Zero-Spin-Gap Half-Metal V₂NiAl into n-Si at Room Temperature

In recent times, an engrossing and newly discovered class of materials with unique electronic band properties, namely, zero-spin-gap half-metal, has gained acute attraction worldwide because of its remarkable transport features that might be employed in spintronic device applications. In this work, polycrystalline high-quality thin films of a zero-spin-gap half-metal V2NiAl (VNL) with spin gapless semiconducting (SGS) behavior have been deposited on single-crystalline n-type Si(100) wafer utilizing electron beam physical vapor deposition (EBPVD) system under high vacuum, producing a very uniform, even, and smooth film surface with full coverage. This ferromagnetic film is realized to crystallizing in the cubic XA structure (CuHg2Ti type), exhibiting a saturation magnetization of 0.92 μB/f.u. at room temperature (300 K) and a Curie temperature (TC) of ∼657 K. The value of the temperature coefficient of resistance (TCR) of the VNL compound in thin-film form is found to be −1.91 × 10–9 Ω m K–1. This value is very close to the temperature coefficient of resistance values of well-established SGSs, which are already reported in the literature. The room-temperature electrical injection of spin-polarized carriers and their accumulation and detection in nonmagnetic semiconductor (n-type silicon) have been successfully investigated employing a three-terminal (3-T) Hanle device using VNL as a ferromagnetic spin injector through a thin native SiO2 tunnel barrier layer. The estimated much improved values of spin diffusion length (LSD = 452 nm) and spin lifetime (τ = 0.57 ns) of the injected spin-polarized carriers at 300 K make V2NiAl a very promising material for upcoming spin-based electronic device applications.