Carrier induced magnetism in dilute Fe doped Ge1−xSbx thin films

•Fe0.01Ge1−xSbx alloy thin films shows semiconducting nature.•Value of resistivity & activation energy increases with increase in Sb concentration.•Films exhibit magnetism even in such low concentrations of Fe (∼0.01) in GeSb system.•No Fe clusters or magnetic phases observed which may have given rise to magnetism.•Magnetic interaction seems to be due to Sb donor impurity charge carriers.

Thin films of Fe0.01Ge1−xSbx (x = 0.01, 0.05, 0.10) alloys were prepared by thermal evaporation technique. Characterization of these thin films was done using High Resolution X-Ray Diffraction (HRXRD), Two Probe Resistivity measurement, Atomic Force Microscopy (AFM) and Magnetic Force Microscopy (MFM) respectively. The resistivity results show that activation energy increases with increase in Sb concentration. The low temperature conduction is explained by Variable Range-Hopping mechanism, which fits very well for the whole temperature range. The Arrhenius plot reveals semiconducting behavior. The AFM images of alloys show almost uniform particle size distribution with average particle size varying from 35 to 60 nm with increase in Sb concentration. The MFM images corresponding to the AFM images show the films exhibiting ferromagnetic interactions at room temperature. The average magnetic domain sizes were observed to increase from 43 to 68 nm with increase in Sb concentration from x = 0.01 to x = 0.10.