Perpendicular
magnetic anisotropy (PMA) is a determining factor
for the realization of nonvolatile information storage devices with
high efficiency and thermal stability. In this work, a new spin gapless
semiconductor Mn2.25Co0.75Ga0.5Sn0.5 Heusler alloy with an inter-spin zero gap was first designed
theoretically. The Mn2.25Co0.75Ga0.5Sn0.5 bulk was prepared successfully in experiment. The
effects of interfacial termination, oxidation, and film thickness
on the magnetic anisotropy of Mn2.25Co0.75Ga0.5Sn0.5/MgO (MCGS/MgO) heterostructures are investigated
systematically by first-principles calculations. The results show
that all the Mn(A)Mn(C)GaSn-, Mn(A)Mn(C)CoGaSn-, Mn(B)GaSnI-, and Mn(B)GaSnII-terminated MCGS/MgO heterostructures
(called as AC1, AC2, BD1, and BD2 models, respectively) present PMA,
which mainly derives from the interfacial and surficial MCGS layers.
Furthermore, the PMA of MCGS/MgO heterostructures can be preserved
in a large range of interfacial oxidization (up to ±50%). With
MCGS thickness increasing from 5 to 16 monolayers, the PMA of MCGS/MgO
heterostructures with an AC-type surface decreases significantly.
However, the PMA of BD-type surface models is relatively robust to
the thickness of the MCGS layer, and the magnetic anisotropy always
points to the out-of-plane direction. Therefore, MCGS Heusler alloy
is a new promising spin gapless semiconductor candidate for spintronics
applications. The robust and tunable PMA in MCGS/MgO heterostructures
offers the possibility for developing nonvolatile data memory devices.