Role of nitrogen on the magnetic properties of MBE grown Mn0.04Ge0.96 films

Abstract

We report the role of nitrogen on the distribution of Mn atoms and ferromagnetism in Mn0.04Ge0.96 films. High quality Mn0.04Ge0.96 films are obtained by sequential evaporation of stacked Mn and Ge layers on Si (100) substrate in N2 environment. The experimental results reveal that the films grown under 5×10−5Torr N2 partial pressure exhibit improved crystallinity and magnetic properties when compared to vacuum deposited films. Correlating the results of electron spin resonance (ESR) and x-ray photoelectron spectroscopy (XPS) studies with magnetic measurements, we have found that introduction of N2 during growth effects the distribution of Mn atoms in Ge. Incorporation of nitrogen into the films and degree of magnetic ordering was obtained from XPS spectra and line shape analysis of ESR spectra. In the presence of nitrogen, enhancement in Curie temperature is associated with the increase in the number of active Mn atoms, however promoted Mn diffusion leads to formation of Mn5Ge3 clusters.