Kerber Nico, Ksenzov Dmitriy, Freimuth Frank, Capotondi Flavio, Pedersoli Emanuele, Lopez-Quintas Ignacio, Seng Boris, Cramer Joel, Litzius Kai, Lacour Daniel, Zabel Hartmut, Mokrousov Yuriy, Kläui Mathias, Gutt Christian
Institut für Physik, Johannes Gutenberg-Universität Mainz, 55099, Mainz, Germany.
Graduate School of Excellence Materials Science in Mainz, 55128, Mainz, Germany.
Nat Commun. 2020 Dec 9;11(1):6304. doi: 10.1038/s41467-020-19613-z.
While chiral spin structures stabilized by Dzyaloshinskii-Moriya interaction (DMI) are candidates as novel information carriers, their dynamics on the fs-ps timescale is little known. Since with the bulk Heisenberg exchange and the interfacial DMI two distinct exchange mechanisms are at play, the ultrafast dynamics of the chiral order needs to be ascertained and compared to the dynamics of the conventional collinear order. Using an XUV free-electron laser we determine the fs-ps temporal evolution of the chiral order in domain walls in a magnetic thin film sample by an IR pump - X-ray magnetic scattering probe experiment. Upon demagnetization we observe that the dichroic (CL-CR) signal connected with the chiral order correlator mm in the domain walls recovers significantly faster than the (CL + CR) sum signal representing the average collinear domain magnetization m + m. We explore possible explanations based on spin structure dynamics and reduced transversal magnetization fluctuations inside the domain walls and find that the latter can explain the experimental data leading to different dynamics for collinear magnetic order and chiral magnetic order.
虽然由Dzyaloshinskii-Moriya相互作用（DMI）稳定的手性自旋结构有望成为新型信息载体，但其在飞秒-皮秒时间尺度上的动力学却鲜为人知。由于体相海森堡交换和界面DMI这两种不同的交换机制同时起作用，因此需要确定手性序的超快动力学，并与传统共线序的动力学进行比较。我们使用极紫外自由电子激光，通过红外泵浦- X射线磁散射探针实验，确定了磁性薄膜样品中畴壁上手性序的飞秒-皮秒时间演化。在退磁过程中，我们观察到与畴壁上手性序关联器mm相关的二向色性（CL-CR）信号的恢复速度明显快于代表平均共线畴磁化强度m + m的（CL + CR）和信号。我们基于自旋结构动力学和畴壁内横向磁化涨落的减小探索了可能的解释，发现后者可以解释实验数据，从而导致共线磁序和手性磁序具有不同的动力学。
