Interfacial exchange coupling in cubic Heusler Co2FeZ (Z = Al and Si)/tetragonal Mn3Ga bilayers

Abstract

We have fabricated bilayer films of tetragonal Heusler-like D022 Mn3Ga and cubic Heusler Co2FeZ (Z = Si and Al) on (100) single-crystalline MgO substrates and investigated their structural and interfacial exchange coupling. The coupling in the Mn3Ga/Co2FeAl bilayer was either ferromagnetic or antiferromagnetic, depending on annealing temperature, whereas only antiferromagnetic exchange coupling was observed in the Mn3Ga/Co2FeSi bilayers. The effects of annealing on the structure and coupling strength in the bilayers are discussed.

Antiferromagnetic coupling in perpendicularly magnetized cubic and tetragonal Heusler bilayers

“…The absolute values of negative J ex are comparable to those evaluated in the FeCo/MnGa bilayers [9] and larger than those in Co 2 FeSi (Al)/MnGa [12].…”

“…However, there are no reports on such bilayer and also magnetic coupling of CMS and MnGa, which is fundamentally important to obtain perpendicular magnetization of CMS. We recently reported that MnGa film with interlayers of B2-ordered Co 2 FeSi (Al) cubic Heusler alloys exhibits AF (ferromagnetic and AF) Jex [12]. Therefore, it is interesting to study MnGa film with a CMS interlayer.…”

Structural and magnetic properties of cubic and tetragonal Heusler alloy bilayers

“…To evaluate J ex , the thickness of the Heusler film was fixed at 20 nm. To estimate H + and H − , an P-MOKE measurement was employed, consistent with reported values estimated from VSM hysteresis in previous studies[33,34]. Although both method yield the same result, it is easier to estimate H + and H − from a P-MOKE hysteresis loop than a VSM hysteresis loop.…”

“…The film com- Refs. [33,34] properties, an X-ray diffractometer with Cu K α radiation was used. To examine the interfacial properties and element distribution of the CMS/MnGa structure, high-resolution transmission electron microscopy (HRTEM) and energydispersive X-ray spectroscopy (EDX) were used, respectively.…”

“…However, there are no reports on such bilayers or the magnetic coupling of Cobased cubic Heusler alloys and MnGa, which is of fundamental importance to obtain the perpendicular magnetization of Co-based cubic Heusler alloys. We recently reported the epitaxy of bilayer films consisting of tetragonal Heuslerlike D0 22 -MnGa and cubic Co-based Heusler alloys on (100) single-crystalline MgO substrates at different annealing temperatures [33,34]. Therefore, in this work, the structural and magnetic properties of Heusler/MnGa bilayer films will be presented in more details for different Heusler alloys: Co 2 FeAl (CFA), Co 2 FeSi (CFS), Co 2 MnAl (CMA), and Co 2 MnSi (CMS).…”