Magnetic properties of magnetite thin films close to the Verwey transition

摘要

Temperature dependence of the magnetic properties of magnetite thin film across the Verwey transition has been investigated. As the temperature is decreased, the magnetization of the film in a fixed field showed a sharp decrease close to the Verwey transition temperature (T_V). The M-H loops of the film have been recorded at various temperatures below and above T_V. It is found that film does not saturate at any temperature and saturation becomes more difficult below T_V. While cooling through T_V, the extrapolated value of magnetization to infinite field (Q), calculated from the numerical fit 4πM = Q [1-(H~*/H)~(1/2)], does not show a drop, but the coefficient indicating difficulty in saturation (H~*) shows a sharp rise as does the coercivity.