Theoretical scheme of nonvolatile strain-switchable high/low resistance based on novel strain-tunable magnetic anisotropy in the Mn 2.25 Co 0.75 Ga 0.5 Sn 0.5 /MgO superlattice.

It is highly desirable to effectively tune electronic and magnetic properties using simple means such as applying an external electrical field or strain in spintronics research. Here, we investigate the strain manipulation of the electronic structure and magnetic anisotropy in (Mn 2.25 Co 0.75 Ga 0.5 Sn 0.5 ) 2 /(MgO) 1 superlattices using first-principles calculations, where Mn 2.25 Co 0.75 Ga 0.5 Sn 0.5 (MCGS) is a newly proposed spin gapless semiconductor with 100% spin polarization. We report that -3 to -5% compressive strain and 1 to 2% tensile strain induce the (MCGS) 2 /(MgO) 1 superlattice to present half-metallic character with 100% spin-polarization. More importantly, biaxial strain has the ability to modify the magnetic anisotropy of the (MCGS) 2 /(MgO) 1 superlattice effectively. The easy magnetization axis can automatically reverse between the out-of-plane and in-plane directions by applying compressive and tensile strain to the MCGS layer. Remarkably, the perpendicular magnetic anisotropy (PMA) of the (MCGS) 2 /(MgO) 1 superlattice increases almost linearly with the increase in compressive strain, while the in-plane magnetic anisotropy (IMA) under tensile strain shows a trend of initially increasing and then decreasing. Actually, strain can be generated by depositing (MCGS) 2 /(MgO) 1 films on ferroelectric substrates. Thus, we propose a new scheme of nonvolatile solely strain-switchable (usually electrically induced) high/low resistance in magnetic tunnel junctions without the aid of a magnetic field. Our results will be important for exploring and realizing stain involved high-performance spintronic devices.