Room temperature electrical spin injection from a new spin gapless ferromagnetic semiconducting inverse Heusler alloy Mn2CoSi into p-Si via SiO2 tunnel barrier

Abstract

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.

Transport properties of Heusler compounds and alloys

“…Very recently, Maji and Nath fabricated Mn 2 CoSi/SiO 2 /p-Si heterostructure utilizing the electron beam physical vapour deposition technique. They demonstrated pure spin injection from Mn 2 CoSi via the SiO 2 tunnel barrier [269]. This indicates that Mn 2 CoSi/SiO 2 can be useful for developing a spin injection tunnel contact.…”

Enhanced Spin Accumulation in Semiconductor at Room Temperature Using Ni0.65Zn0.35Fe2O4(NZFO) as Spin Injector in NZFO/MgO/p-Si Device

“…In order to inject as well as to detect spins in semiconductors, the three-terminal Hanle structure (Maji and Nath, 2019;Maji and Nath, 2020) has been constructed with the help of the vacuum masking method. The 3-T tunnel contacts ("a", "b", and "c"), made on the Hanle device having the dimension of 200 μm 2 × 300 μm 2 , are well separated from each other by a distance of 300 μm (≫ spin diffusion length).…”

“…Here, τ is the spin relaxation time or spin lifetime (Maji and Nath, 2020;Maji and Nath, 2019). The obtained Hanle signal can be best fitted by Eq.…”

Effect of Disorder and Strain on Spin Polarization of a Co2FeSi Heusler Alloy

“…The performance of spin-based devices depends on how much a spin-polarized carrier can move into the SC from a ferromagnetic (FM) electrode. There have been several experimental and theoretical reports on electrical injection and detection of spin signals in FM/SC junctions through insulating tunnel barriers. ,− One avenue by which this can be achieved is by measuring magnetic field-dependent electrical transport properties in FM/SC heterojunctions with a tunnel barrier in between. , It is found that except for being an efficient spin injector, the FM/SC heterostructure can also act as a magnetic diode. , Recently, the generation and detection of spin polarization were demonstrated using a Heusler alloy (HA) as a ferromagnet and native SiO 2 as a tunnel barrier . The main advantage of using SiO 2 is to overcome conductivity mismatch between the FM film and SC. , High spin injection is required to gain large spin current, for which HAs are the best materials due to their attractive properties.…”

“…11,12 Recently, the generation and detection of spin polarization were demonstrated using a Heusler alloy (HA) as a ferromagnet and native SiO 2 as a tunnel barrier. 13 The main advantage of using SiO 2 is to overcome conductivity mismatch between the FM film and SC. 14,15 High spin injection is required to gain large spin current, for which HAs are the best materials due to their attractive properties.…”