GdFeCo磁光薄膜中RE-TM反铁磁耦合与激光感应超快磁化翻转动力学研究

RE-TM antiferromagnetic coupling and laser induced ultrafast magnetization reversal dynamics in GdFeCo magneto-optical films

使用飞秒时间分辨抽运-探测磁光克尔光谱技术,研究了激光加热GdFeCo磁光薄膜跨越铁磁补偿温度时稀土-过渡金属(RE-TM)反铁磁交换耦合行为和超快磁化翻转动力学.实验观察到由于跨越铁磁补偿温度、净磁矩携带者交换而引起的磁化翻转反常克尔磁滞回线以及在同向外磁场下,反常回线上大于和小于矫顽力部分的饱和磁化强度不同,显示出GdFeCo中RE与TM之间的非完全刚性反铁磁耦合.在含有Al导热底层的GdFeCo薄膜上观测到饱和磁场下激光感应磁化态翻转及再恢复的完整超快动力学过程.与剩磁态的激光感应超快退磁化过程比较,发现外磁场似乎并不影响磁畴结核和扩张速率,只影响磁化方向.

The RE-TM antiferromagnetic coupling behavior and magnetization reversal dynamics in passing through the fermimagnetic compensation temperature（T_m） due to laser heating of GeFeCo films are investigated using femtosecond time-resolved pump-probe Kerr spectroscopy.Owing to sample temperature passing through T_m and hence the exchange of net magnetic moment carriers,an abnormal hysteresis loop is observed.The saturation magnetization difference between magnetization states above and below coercive field is found under a same direction of magnetic field,which reveals the incomplete rigid coupling between RE and TM sub-lattices in GdFeCo.A complete ultrafast magnetization reversal and recovery dynamic process is experimentally observed at the saturation magnetic bias on the sample with Al heat sink layer.Besides,by comparing magnetization reversal at saturation magnetic bias with magnetization recovery at remanence,it was found that the magnetic field applied externally does not affect the rate of domain nucleation and growth,but only their magnetization direction.