Achieving perpendicular anisotropy in half-metallic Heusler alloys for spin device applications

Abstract

Various full Heusler alloys are interfaced with MgO and the magnetic properties of the Heusler-MgO junctions are studied. Next to MgO, the cubic Heusler system distorts to a tetragonal one, thereby inducing an anisotropy. The half-metallicity and nature of anisotropy (in-plane or perpendicular) in the Heusler-MgO system is governed mostly by the interface Heusler layers. There is a trend that Mn-O bonding near the MgO-Heusler junction results in perpendicular anisotropy. The ability to remain half-metallic and have perpendicular anisotropy makes some of these alloys potential candidates as free-layers in Spin Transfer Torque Random Access Memory (STT-RAM) devices, particularly, Cr2MnAs-MgO system with MnAs interface layers and Co2MnSi-MgO system with Mn2 interface layers.

Magnetoresistive Random Access Memory

“…There have been a few approaches to address this, e.g. by using interfacial anisotropy [43] or creating a superlattice of two alternating distinct half-metallic materials [94].…”

Perpendicular magnetic anisotropy in Mn2CoAl thin film

“…Since the amount of Mn atom is twice as much as that of Co atom in Mn 2 CoAl film, it is hard to believe that Mn-O bonding has no contribution to PMA. Actually, a strong PMA in the Mn-containing Heusler/MgO system governed by the Mn-O bonding has been revealed by the ab inito calcuation 18 and our another work about the PMA of Co 2 MnSi. 30 Our results to some extent provide experimental evidence on this prediction.…”

Magnetic Tunnel Junctions with a Nearly Zero Moment Manganese Nanolayer with Perpendicular Magnetic Anisotropy

“…The PMA in this study could stem from the interface of the Mn nanolayer and the crystalline oxide of MnO or MgO. This is because the interface PMA may arise as a result of the Mn−O bonding that was discussed for the Heusler alloy/MgO interface terminated by Mn elements, 29 the mechanism being similar to that for the interface PMA arising from the electron orbital hybridization for Fe and O atoms at the Fe/MgO interface. 30 The presence of the interfacial PMA is also in accordance with the VCMA effect observed, as the electric field changes the electronic structure and electron population within the screening length, which is typically 1−2 MLs in the case of metals.…”