The Magnetic and Magnetooptical Properties of Thin Films of Manganese Antimonide

Available from UMI in association with The British Library. The magnetic, structural, optical, and magneto -optical properties of manganese-antimony based alloy films, prepared by r.f. sputtering have been investigated. The films were deposited onto substrates of plain glass, glass coated with a film of manganese, and glass coated with a film of antimony. Measurements have been made on three sets of nine Mn_{rm x}Sb _{rm 1-x} film samples, in the range 0.13 < x < 0.83 whose thickness spans the range 200nm to 400nm, the thickness of the Mn and Sb pre-coatings ranged between 100nm and 300nm. The magnetic properties have been assessed from magnetic hysteresis loops obtained using a sensitive vibrating sample magnetometer. The optimum saturation magnetization value is 574emu/cc and H_{rm c} ~ 1360e. The Mn_ {rm x}Sb_{rm 1-x} films deposited on Sb coated glass show that the nature of the substrate has a marked influence on the magnetic properties. The polar Kerr rotation was measured using a polar Kerr hysteresis loop plotter and the optimum value was found to be 0.19^ circ. Accurate values of the optical constants of each film have been obtained in the wavelength range 400nm-800nm from relative photometric measurements made under optimised experimental conditions. Numerical computation study was made of the optimum conditions, this involved both the accuracy and sensitivity of the optical constants to the experimentally measured parameters. The first order magneto -optical constants have been evaluated from measurements of the transverse Kerr effect also made under optimised experimental conditions. The optical spectra of Mn_{ rm x}Sb_{rm 1-x} films, at a particular composition, is observed to be featureless over the wavelength range investigated. However a variation in the optical constants is observed with a change in film composition. The optical conductivity is high for disordered films but low for ordered films. The magnetic, optical and magneto-optical measurements were also made on films of PtMnSb. The as-deposited amorphous films were found to begin crystallisation at 180 ^circC and become ferromagnetic. The annealed films became transparent with an in-plane easy axis of magnetization. A dramatic change was recorded in the optical properties as the films went from an initial disordered and non-magnetic state to an ordered and ferromagnetic state, upon annealing. The saturation magnetization, M _{rm s} is 550emu/cc, which is close to the value of the bulk PtMnSb alloy. The coercivity is 1600e and the polar Kerr rotation is 0.77 ^circ. The optical and magneto-optical constants have been used to predict the polar Kerr rotation. A good agreement is found between predicted values and the experimentally measured results.