Ultrafast demagnetization in CoPt/sub 3/ alloy films

Summary form only given.A dynamical magnetic phase transition has been observed in CoPt/sub 3/ alloy films. This phase transition, which is consistent with the ferro-paramagnetic transition, occurs with a characteristic time of about 100 fs, i.e., comparable with the pulse duration (120 fs). This ultrafast demagnetization demonstrates the feasibility of ultrafast magnetooptic devices. This result could lead to even faster magnetic effects using shorter pulses and/or other materials.