Magnetic field induced modification of the incommensurate antiferromagnetic structure of Fe-doped MnNiGe alloys

The evolution of the magnetic structure of Fe-doped MnNiGe alloys of nominal compositions MnNi0.75Fe0.25Ge and Mn0.85Fe0.15NiGe has been probed through neutron powder diffraction (NPD) experiments in the presence of external magnetic fields (H). Application of external H results in a significant decrease in the antiferromagnetic satellite peak's intensities along with a considerable change in the incommensurate propagation vector kAFM=(ka,0,0). In addition, a reasonable increase in some of the nuclear reflections has also been noticed, which can clearly be described by the ferromagnetic propagation vector kFM=(0,0,0). Our analysis confirms the gradual rotation of magnetic moments towards the a axis with increasing H and eventual realization of ferromagnetic arrangement at higher applied H.