Magneto-electric coupling at metallic surfaces

磁电耦合允许通过施加电场来影响物质的磁性状态。这种效应主要在绝缘多铁性或半导体铁磁体中观察到，而在金属中则基本上被忽略，因为电场无法深入金属。 然而，在金属表面上，电场既可以引起电子状态的变化（例如d带填充），也可以引起最顶层原子层的表面弛豫。在本计划中，我们将利用扫描隧道显微镜和从头算的方法，分别从实验和理论两方面研究磁性薄膜和表面金属铁磁体中的磁电耦合。特别是，铁磁体心立方（bcc）和反铁磁体面心立方（fcc）铁之间的相变通过局部电场的应用将是焦点，包括过渡动力学方面和使用这种效果的可能性作为数据存储时，使用的Fe（IIO）面心立方铁。此外，电场对磁性薄膜自旋重取向转变附近的效果将被研究。

Magneto-electric coupling allows to influence the magnetic state of matter by the application of an electric field. This effect has mostly been observed in insulating multiferroics or semiconducting ferromagnets and has been largely ignored for metals, as the electric field is incapable to penetrate deeply into metals. On metallic surfaces, however, the electric field can both induce a change of the electronic state (e.g. d-band filling) and of the surface relaxation of the topmost atomic layer. In this proposal, the magneto-electric coupling in ultrathin magnetic films and the surface metallic ferromagnets will be studied experimentally by scanning tunneling microscopy and theoretically by ab inito methods. In particular, the phase transition between ferromagnetic body centred cubic (bcc) and antiferromagnetic face centred cubic (fcc) iron by the application of local electric fields will be in the focus, including aspects of the transition kinetics and the possibility to use this effect as for data storage when using the Fe(IIO) surface of bcc iron. Further, the effect of electric fields on thin magnetic films near a spin reorientation transition will be studied.