Optical and magnetic properties of MnBi formed directly by ion beam mixing

Abstract

Multilayers of Mn/Bi were irrradiated with 400 keV Xe+ at temperatures from 80 to 550 K. Ferromagnetic MnBi layers oriented perpendicular to the substrate surface were formed directly at mixing temperatures from room temperature (RT) to 500 K. The measurements of Curie point and optical Faraday rotation revealed that 60–70 at. % of MnBi ion-mixed at RT is the metastable phase (QIITP: quenched high temperature phase). The fraction of QIITP is reduced with increase in mixing temperature. It was also found that ion beam mixing yields a pronounced protection effect against the deterioration of MnBi in a moist atmosphere. A detailed discussion is given on the kinetics of ion beam mixing and the growth mechanism of the metastable MnBi grains.