Berlin 2018 – scientific programme

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DS: Fachverband Dünne Schichten

DS 31: Poster Session II

DS 31.5: Poster

Thursday, March 15, 2018, 11:15–13:15, Poster F

Ge₂Fe thin films grown by solid-phase epitaxy — •Samuel Gaucher¹, Bernd Jenichen¹, Michael Hanke¹, Achim Trampert¹, Holm Kirmse², Steven C. Erwin³, and Jens Herfort¹ — ¹Paul-Drude-Institut für Festkörperelektronik, Berlin, Germany — ²Humboldt-Universität zu Berlin, Berlin, Germany — ³U. S. Naval Research Laboratory, Washington, D. C., USA

To grow an epitaxial semiconductor over a ferromagnetic metal, a solid-phase epitaxy (SPE) approach was recently developed, whereby amorphous Ge is crystallized slowly by annealing over Fe₃Si. It was realized that a sufficiently thin Ge layer would incorporate Fe and Si atoms to form an ordered superlattice, with 2D planes of Fe atoms interposed between tetragonal Ge formations. This crystal structure is understood as Ge₂Fe (with some Si on Ge sites), a compound that is not energetically stable as a bulk material. By growing Fe₃Si and Ge in the right proportions (1:3), it was possible to use SPE to achieve isolated single-crystalline Ge₂Fe films, directly on GaAs substrates, with thicknesses ranging from 8 to 20 nm. Ge₂Fe thin films are ferromagnetic at low temperature and show strong magnetocrystalline anisotropy, with thickness dependent coercivity on the order of 200 Oe along the easy magnetization axis. The material has a room temperature resistivity ρ ∼ 8× 10⁻⁶Ω m along the Fe basal planes, which decreases as a metal when temperature is lowered. Alike other thin Fe-Ge compounds, Ge₂Fe is a possible candidate to host topological magnetic skyrmions, among other interesting micromagnetic phenomena.