Correlation between morphology and magnetic properties of Fe66Ge34 films

We demonstrate the effect of varying surface temperature during co-evaporation of iron and germanium on the film morphology, segregation, magnetic anisotropy, and magnetization configuration and reversal. Using nominally the same growth conditions with and without aluminum seed layer on silicon nitride, different mounting strategies are discussed. Our results divulge the inevitable increase in surface temperature due to radiation heating that alters the structural and chemical short-range order. Films synthesized at room temperature while rotating the substrate are generally isotropic and nanogranular, while low-temperature homogeneous materials reveal a sizable uniaxial, in-plane anisotropy and striped domain formation. Our work underlines the need for low-temperature depositions to synthesize amorphous materials with tailored short-range order and functionality and informs the nascent field of amorphous quantum materials.