Windsor Y W, Zahn D, Kamrla R, Feldl J, Seiler H, Chiang C-T, Ramsteiner M, Widdra W, Ernstorfer R, Rettig L
Department of Physical Chemistry, Fritz Haber Institute of the Max Planck Society, Faradayweg 4-6, 14195 Berlin, Germany.
Institute of Physics, Martin-Luther-Universität Halle-Wittenberg, 06120 Halle, Germany.
Phys Rev Lett. 2021 Apr 9;126(14):147202. doi: 10.1103/PhysRevLett.126.147202.
We use femtosecond electron diffraction to study ultrafast lattice dynamics in the highly correlated antiferromagnetic (AFM) semiconductor NiO. Using the scattering vector (Q) dependence of Bragg diffraction, we introduce Q-resolved effective temperatures describing the transient lattice. We identify a nonthermal lattice state with preferential displacement of O compared to Ni ions, which occurs within ∼0.3 ps and persists for 25 ps. We associate this with transient changes to the AFM exchange striction-induced lattice distortion, supported by the observation of a transient Q asymmetry of Friedel pairs. Our observation highlights the role of spin-lattice coupling in routes towards ultrafast control of spin order.
我们使用飞秒电子衍射来研究高度关联的反铁磁（AFM）半导体NiO中的超快晶格动力学。利用布拉格衍射的散射矢量（Q）依赖性，我们引入了描述瞬态晶格的Q分辨有效温度。我们确定了一种非热晶格状态，其中O离子相对于Ni离子有优先位移，这种情况在约0.3皮秒内出现并持续25皮秒。我们将此与AFM交换严格约束诱导的晶格畸变的瞬态变化相关联，这一变化得到了弗里德尔对瞬态Q不对称性观测结果的支持。我们的观测突出了自旋 - 晶格耦合在超快控制自旋序途径中的作用。
