Chiral spin structures in antiferromagnet-ferromagnet bilayers

在铁磁体与重金属（如Pt和Ir）的界面处，可以看到原子磁性结构中的手征扭曲，导致拓扑稳定的磁畴，称为skyrmion。这种手性磁性物体在磁存储器和传感器技术中具有潜在的应用。Mn基反铁磁体也含有重元素（例如Pt，Ir），本项目将研究这种反铁磁体与铁磁层之间界面处的手征磁性结构。使用反铁磁体的原因是它们在与铁磁体的界面处提供交换偏置，这可能有助于稳定skyrmion，以及诱导手性的Dzyaloshinskiii-Moriya相互作用（R.A. Khan等人，Phys. Rev. B 98，064413（2018））。流过反铁磁体的电流还可以提供自旋力矩，以推动斯基尔米恩通过铁磁体，这将具有很大的基础和技术意义。这是利兹大学和美因茨约翰尼斯古滕贝格大学的联合项目。单晶反铁磁体-铁磁体层将被沉积，并在内部和大型同步加速器设施中进行结构和磁性表征。我们正在寻找一个有凝聚态物理，材料科学或类似背景的积极主动的学生，最好有磁性或薄膜特性的经验。利兹大学的凝聚态研究小组是英国在纳米磁学和自旋电子学方面处于领先地位。它拥有一套广泛的材料生长、纳米级制造和样品表征设施。在2011年CHE和2017年上海排名中，美因茨大学物理系被选为欧洲优秀组，最近被德国研究基金会2018年德国所有物理系排名第一。它在凝聚态物理领域尤其强大，并设有美因茨卓越材料科学研究生院（www.mainz.uni-mainz.de）。

Chiral twists in atomic magnetic structure are seen in ferromagnets at the interface with heavy metals such as Pt and Ir, leading to topologically stable magnetic domains known as skyrmions. Such chiral magnetic objects have potential applications in magnetic memory and sensor technology. Mn-based antiferromagnets also contain heavy elements (e.g. Pt, Ir), and this project will investigate chiral magnetic structure at the interface between such antiferromagnets and a ferromagnetic layer. The reason for using antiferromagnets is that they provide an exchange bias at the interface with a ferromagnet that might help to stabilise skyrmions, as well as a Dzyaloshinskii-Moriya interaction that induces the chirality (R.A. Khan et al., Phys. Rev. B 98, 064413 (2018)). A current flowing through the antiferromagnet may also provide a spin torque to push the skyrmion through the ferromagnet, which would be of great fundamental and technological interest.This is a joint project between the University of Leeds and the Johannes Gutenberg University of Mainz. Single crystal antiferromagnet-ferromagnet layers will be deposited and undergo structural and magnetic characterisation, both in-house and at large-scale synchrotron facilities. We are looking for a motivated student with a background in condensed matter physics, materials science or similar, preferably with experience in magnetism or thin film properties. The Condensed Matter group at the University of Leeds is one of the U.K.'s leading research groups in nanomagnetism and spintronics. It possesses an extensive suite of facilities for materials growth, nanoscale fabrication and sample characterisation. In the 2011 CHE & 2017 Shanghai rankings the physics department at the University of Mainz was selected for the excellence group in Europe and recently was ranked first by the German Research Foundation 2018 ranking of all Physics Departments in Germany. It is particularly strong in the area of condensed matter physics and houses the Graduate School of Excellence Materials Science in Mainz (www.mainz.uni-mainz.de).