Epitaxial growth and magnetic properties of Mn5Ge3/Ge and Mn5Ge3Cx/Ge heterostructures for spintronic applications

Abstract

The development of active spintronic devices, such as spin-transistors and spin-diodes, calls for new materials that are able to efficiently inject the spin-polarized current into group-IV semiconductors (Ge and Si). In this paper we review recent achievements of the synthesis and the magnetic properties of Mn5Ge3/Ge and carbon-doped Mn5Ge3/Ge heterostructures. We show that high crystalline quality and threading-dislocation free Mn5Ge3 films can be epitaxially grown on Ge(111) substrates despite the existence of a misfit as high as 3.7% between two materials. We have investigated the effect of carbon doping in epitaxial Mn5Ge3 films and show that incorporation of carbon into interstitial sites of Mn5Ge3 can allow not only enhancement of the magnetic properties but also an increase of the thermal stability of Mn5Ge3. Finally, toward the perspective to realize Ge/Mn5Ge3/Ge multilayers for spintronic applications, we shall show how to use carbon to prevent Mn out-diffusion from Mn5Ge3 during Ge overgrowth on top of Mn 5Ge3/Ge heterostructures. The above results open the route to develop spintronic devices based on Mn5Ge3C x/Ge heterostructures using a Schottky contact without needing an oxide tunnel barrier at the interface. © 2013 Vietnam Academy of Science & Technology.