Role of the substrate temperature on the growth of Mn5Ge3 thin films by co-deposition of Mn and Ge on Ge(001) substrates by magnetron sputtering

Mn5Ge3 thin films grown on Ge(001) substrates were obtained by co-deposition of pure Mn and Ge elements using rf-magnetron sputtering at different substrate temperatures, Ts (250 °C ≤ Ts ≤ 550 °C) in order to analyze the influence of the substrate temperature on the structural and magnetic properties of the samples. These films were thoroughly studied by reflection high-energy electron diffraction, transmission electron microscopy, atomic force microscopy, and SQUID magnetometry, evidencing the important role of the substrate temperature on the microstructure of the films. For temperatures higher or equal to 350 °C, a crystalline Mn11Ge8 phase also appears in addition of the Mn5Ge3 one, evidenced by the diffraction and magnetic measurements. Additionally, spin-glass-like magnetic behavior is also observed in all the samples (more evident when the Mn11Ge8 phase is small), due to the existence of a layer with spin-glass properties at the Ge/Mn5Ge3 interface caused by the intermixing of Ge and Mn at that interface.