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Inverse Heusler alloys possessing spin gapless semiconducting behavior have drawn great curiosity among researchers in the past few months on account of their unique transport characteristics that can be put into use in spin based electronic device implementations. Thin films of a possible ternary spin gapless semiconductor Mn2CoSi (MCS) inverse Heusler alloy have been deposited on a p-Si (100) substrate using the electron beam physical vapor deposition technique. The as-grown films exhibit a polycrystalline nature having a uniform and smooth surface with full coverage. A magnetic study reveals that the film is ferromagnetically soft along the direction parallel to its plane and its Curie temperature (TC) is much higher than room temperature (300 K). The formation of the MCS/SiO2/p-Si heterostructure is confirmed from cross-sectional transmission electron microscopy and cross-sectional scanning electron microscopy studies. The electronic- and magneto-transport properties of the heterostructure have been studied at various isothermal conditions. From current–voltage characteristics, a conventional magnetic diode like behavior has been observed throughout the working temperature regime of 78–300 K. The temperature coefficient of resistance (TCR) value of the film is estimated to be –2.09 × 10−9 Ω m/K, which is similar to the TCR values of reported spin gapless semiconductors. Room temperature spin injection and detection in a nonmagnetic semiconductor (p-Si) has been carried out using the three-terminal Hanle device in our MCS/SiO2/p-Si heterostructure. The estimated values of spin lifetime (78 ps) and spin diffusion length (167 nm) of the injected carriers at room temperature provide an indication of their industrial importance in future spin based electronic device applications.

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Here, we report fabrication of a high quality exchanged biased trilayer magnetic tunnel junction (MTJ) utilizing a magnetron sputtering system. The MTJ is composed of a type-II spin gapless semiconductor (SGS) Ti2CoSi inverse Heusler alloy (used as a lower electrode), a thin MgO layer (used as a tunnel barrier), and a half-metallic ferromagnet (HMF) Co2MnSi Heusler alloy (used as an upper electrode). Spin dependent transport properties reveal that the micro-fabricated MTJ can act as a reconfigurable magnetic tunnel diode, which lets the electric current to flow in either the forward or reverse path relying on the relative alignment of the magnetization direction of the upper and lower magnetic electrodes. A considerably high on/off current ratio (∼103) and a significantly low turn on voltage (VT) of 0.09 V have been achieved at 5 K for both parallel and antiparallel configurations. Another important characteristic shown by our fabricated MTJ is that it exhibits extremely large tunnel magnetoresistance ratios of 892% at 5 K and 197% at room temperature, which brings to light the utmost importance of using the combination of HMF and SGS materials as magnetic electrodes in a tunnel junction for potential applications in modern spintronic devices. All these exceptional features can undoubtedly nominate CMS/MgO/TCS MTJs as a promising candidate to serve as memory or logic elements in next generation ultra-high density magnetoresistive random access memories together with contemporary spin based electronic devices.

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 (T C) 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 (L SD = 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.