For static magnetic properties of the Co/Ni bilayers, macroscopic hysteresis loops and microscopic magnetic moment distributions have been determined by the object oriented micromagnetic framework（OOMMF）. It is foun...For static magnetic properties of the Co/Ni bilayers, macroscopic hysteresis loops and microscopic magnetic moment distributions have been determined by the object oriented micromagnetic framework（OOMMF）. It is found that when the bilayer systems are fully decoupled, the magnetizations of the two phases reverse separately. The coercivity of the bilayers decreases to a valley value sharply with increasing interfacial exchange coupling and then rises slowly to a platform. On the other hand, we have carried out an atomistic simulation for the laser-induced ultrafast demagnetization of the Co/Ni bilayer. A larger damping constant leads to a faster demagnetization as well as a larger degree of demagnetization, which is consistent with the first-principle theoretical results. For the magnetization recovery process, the damping constant has different influences on the recovery time with various peak electron temperatures, which is ignored in previous atomistic simulations as well as the Landau–Liftshit–Bloch（LLB） micromagnetic calculations. Furthermore, as the interfacial exchange coupling increases, the ultrafast demagnetization curves for Co and Ni become coincident, which is a demonstration for the transition from two-phase phenomenon to single-phase phenomenon.展开更多
研究了光激发反铁磁性绝缘体Cr_2O_3超快退磁动力学.通过对反铁磁性Cr_2O_3的光吸收谱进行分析,计算了不同态之间的能量差.通过解耗散薛定谔方程研究了2.5 e V激发电子从高自旋态到低自旋态的超快动力学过程.利用数值模拟的方法计算出...研究了光激发反铁磁性绝缘体Cr_2O_3超快退磁动力学.通过对反铁磁性Cr_2O_3的光吸收谱进行分析,计算了不同态之间的能量差.通过解耗散薛定谔方程研究了2.5 e V激发电子从高自旋态到低自旋态的超快动力学过程.利用数值模拟的方法计算出反铁磁性绝缘体Cr_2O_3的退磁时间为350飞秒,这个结果与实验结果符合得很好;此外,进一步分析了Cr_2O_3的退磁路径.证明耗散薛定谔方程是研究电子从高自旋态到低自旋态弛豫的一种有效的量子方法.展开更多
基金Project supported by the National Basic Research Program of China(Grant Nos.2015CB921403 and 2016YFA0300701)the National Natural Science Foundation of China(Grant Nos.91622126,51427801,and 51671212)the Natural Science Foundation of Hebei Province,China(Grant No.A2015203021)
文摘For static magnetic properties of the Co/Ni bilayers, macroscopic hysteresis loops and microscopic magnetic moment distributions have been determined by the object oriented micromagnetic framework（OOMMF）. It is found that when the bilayer systems are fully decoupled, the magnetizations of the two phases reverse separately. The coercivity of the bilayers decreases to a valley value sharply with increasing interfacial exchange coupling and then rises slowly to a platform. On the other hand, we have carried out an atomistic simulation for the laser-induced ultrafast demagnetization of the Co/Ni bilayer. A larger damping constant leads to a faster demagnetization as well as a larger degree of demagnetization, which is consistent with the first-principle theoretical results. For the magnetization recovery process, the damping constant has different influences on the recovery time with various peak electron temperatures, which is ignored in previous atomistic simulations as well as the Landau–Liftshit–Bloch（LLB） micromagnetic calculations. Furthermore, as the interfacial exchange coupling increases, the ultrafast demagnetization curves for Co and Ni become coincident, which is a demonstration for the transition from two-phase phenomenon to single-phase phenomenon.
文摘研究了光激发反铁磁性绝缘体Cr_2O_3超快退磁动力学.通过对反铁磁性Cr_2O_3的光吸收谱进行分析,计算了不同态之间的能量差.通过解耗散薛定谔方程研究了2.5 e V激发电子从高自旋态到低自旋态的超快动力学过程.利用数值模拟的方法计算出反铁磁性绝缘体Cr_2O_3的退磁时间为350飞秒,这个结果与实验结果符合得很好;此外,进一步分析了Cr_2O_3的退磁路径.证明耗散薛定谔方程是研究电子从高自旋态到低自旋态弛豫的一种有效的量子方法.
