Direct comparison of thermal and magnetic profiles in "curie point" writing on MnGaGe films

Abstract

Measurements have been made of both the real-time temperature profile and the steady-state magnetization profile achieved in a film of MnGaGe as a result of "Curie point" writing with a GaAs laser pulse. A HeNe laser probe having a half-power diameter of 1 μ was used to measure both profiles. Temperature was measured during and after application of the heat pulse by relating the time-dependent transmission change of the heated area of the film to the temperature-calibrated shift of the absorption edge of MnGaGe. Magnetization information was obtained by measuring the Faraday rotation within the written area after the film had cooled to ambient. A comparison of the two profiles indicates that (a) magnetization reversal occurs at temperatures well below the Curie point, even in the absence of an external bias field, and (b) the critical temperature required for reversal increases with an increase in the size of the heated area. Both results can be explained qualitatively by local demagnetization effects. © 1973 American Institute of Physics.