Max-Born-Institut, Berlin, Germany.
Phys Rev Lett. 2012 Aug 3;109(5):057401. doi: 10.1103/PhysRevLett.109.057401. Epub 2012 Jul 31.
The temporal evolution of the exchange-split Δ(2)-like Σ valence bands of the 4f-ferromagnet gadolinium after femtosecond laser excitation has been studied using angle-resolved photoelectron spectroscopy based on high-order harmonic generation. The ultrafast drop of the exchange splitting reflects the magnetic response seen in femtosecond magnetic dichroism experiments. However, while the minority valence band reacts immediately, the response of the majority counterpart is delayed by 1 picosecond and is only half as fast. These findings demonstrate that laser excitation drives the valence band structure out of magnetic equilibrium.
使用基于高次谐波产生的角分辨光电子能谱研究了飞秒激光激发后 4f 铁磁体钆的交换分裂 Δ(2)-样 Σ 价带的时间演化。交换分裂的超快下降反映了在飞秒磁二色性实验中观察到的磁响应。然而，虽然少数价带立即反应，但多数价带的响应延迟了 1 皮秒，并且速度只有一半。这些发现表明激光激发将价带结构驱动出磁平衡。
