Department of Optical Science and Engineering, Fudan University, Shanghai, China.
Phys Rev Lett. 2011 Nov 11;107(20):207205. doi: 10.1103/PhysRevLett.107.207205.
Pronounced spin precessions are observed in a geometry with negligible canting of the magnetization in ferromagnetic La(0.67)Ca(0.33)MnO(3) thin films using the time-resolved magneto-optical Kerr effect. The precession amplitude monotonically decreases with increasing field, indicating that the coherent spin rotation may be triggered by a transient exchange field and not by demagnetization and/or anisotropy field modulation. We attribute the transient exchange field to emergent antiferromagnetic interactions due to charge transfer and modification of the kinetic energy of e(g) electrons under optical excitation.
在具有铁磁 La(0.67)Ca(0.33)MnO(3) 薄膜的小磁倾斜几何结构中，使用时间分辨磁光克尔效应观察到明显的自旋进动。进动幅度随磁场的增加单调减小，表明相干自旋旋转可能由瞬态交换场触发，而不是由退磁化和/或各向异性场调制触发。我们将瞬态交换场归因于由于电荷转移和 e(g)电子的动能在光激发下的改变而出现的反铁磁相互作用。
