Torija M A, Gai Z, Myoung N, Plummer E W, Shen J
Condensed Matter Sciences Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
Phys Rev Lett. 2005 Jul 8;95(2):027201. doi: 10.1103/PhysRevLett.95.027201. Epub 2005 Jul 5.
In ultrathin film systems, it is a major challenge to understand how a thickness-driven phase transition proceeds along the cross-sectional direction of the films. We use ultrathin Fe films on Cu(111) as a prototype system to demonstrate how to obtain such information using an in situ scanning tunneling microscope and the surface magneto-optical Kerr effect. The magnetization depth profile of a thickness-driven low-spin to high-spin magnetic phase transition is deduced from the experimental data, which leads us to conclude that a low-spin Fe layer at the Fe/Cu interface stays live upon the phase transition. The magnetically live low-spin phase is believed to be induced by a frozen fcc Fe layer that survives a thickness-driven fcc-->bcc structural transition.
在超薄膜系统中，理解厚度驱动的相变如何沿薄膜的横截面方向进行是一项重大挑战。我们使用Cu(111)上的超薄铁膜作为原型系统，来演示如何使用原位扫描隧道显微镜和表面磁光克尔效应获取此类信息。从实验数据中推导出了厚度驱动的低自旋到高自旋磁相变的磁化深度分布，这使我们得出结论，即铁/铜界面处的低自旋铁层在相变过程中保持活性。据信，磁性活性低自旋相是由在厚度驱动的面心立方（fcc）到体心立方（bcc）结构转变中幸存的冻结面心立方铁层诱导产生的。
