Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
Phys Rev Lett. 2012 Dec 14;109(24):247204. doi: 10.1103/PhysRevLett.109.247204. Epub 2012 Dec 12.
We study the magnetic excitations of itinerant helimagnets by applying time-resolved optical spectroscopy to Fe(0.8)Co(0.2)Si. Optically excited oscillations of the magnetization in the helical state are found to disperse to lower frequency as the applied magnetic field is increased; the fingerprint of collective modes unique to helimagnets, known as helimagnons. The use of time-resolved spectroscopy allows us to address the fundamental magnetic relaxation processes by directly measuring the Gilbert damping, revealing the versatility of spin dynamics in chiral magnets.
我们通过对 Fe(0.8)Co(0.2)Si 进行时间分辨光学光谱研究来研究巡游螺旋磁体的磁激发。我们发现，在螺旋态下，光激发的磁化强度振荡随着外加磁场的增加而向低频色散；这是螺旋磁体特有的集体模式的特征，称为螺旋磁激元。时间分辨光谱的使用允许我们通过直接测量 Gilbert 阻尼来解决基本的磁弛豫过程，从而揭示手性磁体中自旋动力学的多功能性。
