Magnetic properties and interfacial characteristics of all-epitaxial Hensler-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.