GdFeCo磁光薄膜飞秒激光感应反常磁滞回线研究

Study of Anomalous Hysteresis Loops Induced by Femtosecond Laser Pulses in GdFeCo Film

该文使用飞秒时间分辨泵浦-探测磁光克尔光谱技术,研究了飞秒激光加热GdFeCo磁光薄膜跨越铁磁补偿温度时,净磁矩方向发生转变而引起磁化反转的反常克尔磁滞回线。通过测量不同激发功率下以及不同泵浦脉冲数下的反常克尔回线,揭示反常回线包含连续脉冲激发产生的积累效应以及外场磁化史的记忆效应,对反常回线的形成起源做了深入探索和详细研究。研究结果对于深入理解GdFeCo合金薄膜中稀土-过渡金属间的反铁磁耦合特性以及磁化反转的机理具有重要意义。

The time-resolved pump-probe magneto-optical Kerr technique was used to study the GdFeCo films excited by femtosecond laser. The anormalous Kerr loops were observed, owing to the fact that the sample temperature passed through the ferromagnetic compensation temperature and then caused the change of the direction of net magnetic moment. The anormalous Kerr loops, which were obtained under different pump fluence and different amount of pump pulses, were revealed contained accumulation effect from continuous pulses pump and memory effect from external magnetic field history. The origin of anom- alous loops was studied in depth. The results were important to further understand the antiferromagnetic coupling property between rare earth sub-lattice and transition metal sub-lattice in GdFeCo and the mech- anism of magnetization reversal.