Magnetization reversal mechanism of double-helix nanowires probed by dark-field magneto-optical Kerr effect
TU Wien（维也纳工业大学）；University of Loughborough（拉夫堡大学）；Instituto de Nanociencia y Materiales de Aragón, CSIC-Universidad de Zaragoza（阿拉贡纳米科学与材料研究所，西班牙科学理事会-萨拉戈萨大学）；Synchrotron SOLEIL（SOLEIL同步辐射中心）；University of Vienna（维也纳大学）；Max Planck Institute for Chemical Physics of Solids（马克斯·普朗克固体化学物理研究所）；Hiroshima University（广岛大学）
Takeaki Gokita, Jakub Jurczyk, Naëmi Leo, Sabri Koraltan, Alberto Anadón, Miguel Ángel Cascales-Sandoval, Rachid Belkhou, Claas Abert, Dieter Suess, Claire Donn… 展开作者
Takeaki Gokita, Jakub Jurczyk, Naëmi Leo, Sabri Koraltan, Alberto Anadón, Miguel Ángel Cascales-Sandoval, Rachid Belkhou, Claas Abert, Dieter Suess, Claire Donnelly, Amalio Fernández-Pacheco
Double-helix (DH) nanowires provide a platform to study the influence of geometric chirality on spin chirality. Their three-dimensional (3D) helical architecture and tunable inter-strand coupling enable control of spin chirality, including the stabilization of topological 3D magnetic states such as helical domains and domain walls, topological stray fields, and extended helical vortex/skyrmion tubes. So far, the study of these and other 3D nanostructures is usually confined to a limited number of magnetic microscopy experiments in large facilities. Here, we investigate the reversal mechanism of a single DH nanowire using Dark-Field magneto-optical Kerr effect (DF-MOKE) magnetometry under external 3D magnetic fields. By analyzing the angular dependence of the DF-MOKE signal, we fit the reversal process using established models for domain-wall nucleation and propagation, finding a characteristic behavior similar to that reported for cylindrical nanowires. Micromagnetic simulations indicate that the reversal process goes through nucleation of the helical vortex tube in a curling manner while ptychographic X-ray magnetic circular dichroism data reveal that this helical vortex tube state forms through a mixed nucleation-propagation process. These observations provide a consistent microscopic picture of reversal mediated by a helical vortex tube extending along the nanowire. Our work provides a comprehensive characterization of magnetization reversal in DH nanowires and demonstrates that DF-MOKE magnetometry is effective for probing reversal mechanisms in single 3D nanostructures. This lab-based approach expands the range of accessible experiments beyond large-scale facilities, enabling extensive exploration of the rich spin states supported by 3D nano-geometries.
Common nonlinear features and spin-orbit coupling effects in the Zeeman splitting of novel wurtzite materials
半导体材料对外部磁场的响应是探测本征电子和自旋相关性质的可靠方法。在这项研究中，我们研究了常见的塞曼分裂功能的新型纤锌矿材料，即InP，砷化铟，和GaAs。我们目前的值为不同的能带的有效g-因子，并表明自旋轨道耦合效应，负责自旋分裂，也有显着的贡献的g-因子。在朗道能级图中，我们发现Tedeschi等人最近在InP纳米线的磁光致发光实验中解释的非线性塞曼分裂[Phys. Rev. B 99，161204（2019）]也存在于InAs，GaAs甚至传统GAN中。这种非线性特征源于A和B价带的特殊耦合，这是纤锌矿晶体对称性和外部磁场破坏时间反演对称性之间相互作用的结果。此外，我们开发了一个分析模型来描述实验的非线性塞曼分裂，并将其应用到InP和GaAs的数据。外推我们的拟合结果，我们发现InP的塞曼分裂达到最大值，这是一个预测，可以在更高的磁场探测。
