Magnetic properties and interfacial characteristics of all-epitaxial Heusler-compound stacking structures

We study magnetic properties and interfacial characteristics of all-epitaxial $D{0}₃\ensuremath{-}{\mathrm{Fe}}₃\mathrm{Si}/L{2}₁$- ${\mathrm{Fe}}_{3\ensuremath{-}x}{\mathrm{Mn}}_x\mathrm{Si}/L{2}₁\ensuremath{-}{\mathrm{Co}}₂\mathrm{FeSi}$ Heusler-compound trilayers grown on Ge(111) by room-temperature molecular beam epitaxy. We find that the magnetization reversal processes can be intentionally designed by changing the chemical composition of the intermediate ${\mathrm{Fe}}_{3\ensuremath{-}x}{\mathrm{Mn}}_x\mathrm{Si}$ layers because of their tunable ferromagnetic-paramagnetic phase-transition temperature. From first-principles calculations, interfacial half metallicity in the ${\mathrm{Co}}₂\mathrm{FeSi}$ layer is nearly expected when the sequence of stacking layers along $\ensuremath{\langle}111\ensuremath{\rangle}$ of the ${\mathrm{Fe}}₂\mathrm{MnSi}/{\mathrm{Co}}₂\mathrm{FeSi}$ interface includes the atomic row of $L{2}₁$- or $B2$-ordered structures. We believe that ${\mathrm{Co}}₂\mathrm{FeSi}/{\mathrm{Fe}}₂\mathrm{MnSi}/{\mathrm{Co}}₂\mathrm{FeSi}$ trilayer systems stacked along $\ensuremath{\langle}111\ensuremath{\rangle}$ will open a new avenue for high-performance current-perpendicular-to-plane giant magnetoresistive devices with Heusler compounds.