Influence of growth conditions on characteristic properties of iron germanium films

This study examines how variations in the growth environment of 20 nm Fe-Ge films, deposited on amorphous silicon nitride using molecular beam epitaxy, affect their material properties. Non-crystalline Fe-Ge, noted for its unique magnetic characteristics, displays unique spin configurations at room temperature in the absence of long-range order—unlike similar metal-semiconductor thin films, which usually require cryogenic conditions to stabilize such configurations. These features arise from the hybridization of iron's d orbitals and germanium's sp band states. The lack of long range order and the observed sensitivity of those magnetic properties to coordination [1,2] motivated the study of how the growth environment affects coordination and in turn magnetic and electronic properties. The talk involves examination of several environmental factors: growth stage (cooled vs. rotatable), substrate holder material (Ta vs. Cu), mounting technique (silver paint vs. Cu clamps), and the presence of an Al seed layer. We employ techniques such as x-ray photoelectron spectroscopy, energy dispersive spectroscopy, x-ray diffraction, atomic force microscopy, as well as magnetometry and transport measurements to analyze the chemical, structural, magnetic, and electronic properties of the samples and relate these to their growth conditions.