Woltersdorf G, Buess M, Heinrich B, Back C H
Simon Fraser University, 8888 University Drive, Burnaby, British Columbia V5A 1S6, Canada.
Phys Rev Lett. 2005 Jul 15;95(3):037401. doi: 10.1103/PhysRevLett.95.037401. Epub 2005 Jul 11.
The time-resolved magnetic response of ultrathin epitaxial Fe(001) films grown on GaAs(001) and covered by Au, Pd, and Cr capping layers was investigated by time and spatially resolved Kerr effect measurements. The magnetization was excited by an in-plane magnetic field pulse using the transient internal field generated at a Schottky barrier while the wavelength of the excitation (resonant mode) was roughly 4 microm. Each of the three cap layers affected the spin relaxation in a unique way. Au cap layers resulted in the bulk Gilbert damping of the Fe film. Pd cap layers caused an additional Gilbert damping due to spin-pump or spin-sink effects. Cr cap layers lead to a strong extrinsic damping which can be described by two-magnon scattering. In this case the strength of the extrinsic damping can be controlled by a field induced shift of the spin wave manifold with respect to the excited k vector.
通过时间分辨和空间分辨的克尔效应测量，研究了生长在GaAs(001)上并覆盖有金、钯和铬覆盖层的超薄外延Fe(001)薄膜的时间分辨磁响应。利用肖特基势垒处产生的瞬态内场，通过面内磁场脉冲激发磁化强度，激发波长（共振模式）约为4微米。三种覆盖层中的每一种都以独特的方式影响自旋弛豫。金覆盖层导致铁薄膜的体吉尔伯特阻尼。钯覆盖层由于自旋泵浦或自旋汇效应导致额外的吉尔伯特阻尼。铬覆盖层导致强烈的非本征阻尼，这可以用双磁子散射来描述。在这种情况下，非本征阻尼的强度可以通过自旋波流形相对于激发k矢量的场致位移来控制。
