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

Vinh Le Thanh, Aurélie Spiesser, Minh-Tuan Dau, Sion F Olive-Mendez, Lisa A Michez and Matthieu Petit

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 Mn₅Ge₃/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