Dual coercive force hysteresis in MnAlGe films

The room temperature coercive force of some MnAlGe films can be substantially altered in a reversible way. The coercive force is reduced by heating to C and then recooling to room temperature. The low coercive force hysteresis loop can be indefinitely cycled as long as the applied field does not exceed a threshold, Hx. The large coercive force can be restored by applying a field greater than Hx. This paper contains the results of experimental observations and calculations of this phenomenon. The experimental observations include magnetic hysteresis measurements and visual observation of the details of the magnetic domain reversal process, using the Faraday effect. A model is proposed to explain this phenomenon. Both the calculations and the experimental observations support the proposed explanation.