Inelastic Neutron Scattering on the self- and self-vacancy-doped MnNiGe alloys

Depending on the doping strategy, a combination of self and self-vacancy-doping significantly modifies the modulation of the incommensurate magnetic structure of the MnNiGe alloy of the magnetic equiatomic alloy family. The pristine MnNiGe alloy was reported to show a helically modulated antiferromagnetic (AFM) structure. Recent neutron powder diffraction results from our group (data recorded at POWGEN diffractometer, ORNL) indicate that helical modulation of the AFM structure remains unperturbed in self-doped alloy, whereas for self-vacancy doped it changes to commensurate. A large change in propagation vector is another critical difference between these two studied alloys. Such a change in AFM modulation may also influence the magnetic excitation behavior (spin wave/spin fluctuation), which is reflected in rich magnetic and magnetofunctional behavior. The present proposal aimed to probe such changes in excitation behavior through inelastic neutron scattering studies at MARI of two doped alloys on nominal compositions Mn1.25Ni0.75Ge and Mn1.04Ni0.86Ge.