Suppression of phase segregations in Ge-Fe-Co-Ni-Mn films by high-entropy effect

Fe-Co-Ni-Mn films doped with different concentrations of Ge were prepared on the Si substrates by using radio frequency magnetron sputtering. Transmission electron microscopy (with an energy dispersive x-ray spectrometer) and an x-ray diffractometer were used to systematically study the microstructure evolution of the Fe-Co-Ni-Mn-Ge films. The results indicate that the Fe-Co-Ni-Mn films doped with a large amount of Ge show significant element segregation after rapid high-temperature annealing. However, with the decrease in the doping amount of Ge to approximately equal molar ratio with magnetic elements, Ge and magnetic elements achieve perfect mutual dissolution at the same annealing conditions, forming single-phase solid solution. Electrical transport tests suggest that its electrical property is close to semiconductors. The mechanism of enhanced mutual solubility between semiconductor elements and magnetic elements is discussed in detail.