Heyne L, Kläui M, Backes D, Moore T A, Krzyk S, Rüdiger U, Heyderman L J, Rodríguez A Fraile, Nolting F, Mentes T O, Niño M A, Locatelli A, Kirsch K, Mattheis R
Fachbereich Physik, Universität Konstanz, Universitätsstrasse 10, D-78457 Konstanz, Germany.
Phys Rev Lett. 2008 Feb 15;100(6):066603. doi: 10.1103/PhysRevLett.100.066603. Epub 2008 Feb 14.
By direct imaging we determine spin structure changes in Permalloy wires and disks due to spin transfer torque as well as the critical current densities for different domain wall types. Periodic domain wall transformations from transverse to vortex walls and vice versa are observed, and the transformation mechanism occurs by vortex core displacement perpendicular to the wire. The results imply that the nonadiabaticity parameter beta does not equal the damping alpha, in agreement with recent theoretical predictions. The vortex core motion perpendicular to the current is further studied in disks revealing that the displacement in opposite directions can be attributed to different polarities of the vortex core.
通过直接成像，我们确定了坡莫合金线和磁盘中由于自旋转移力矩引起的自旋结构变化，以及不同畴壁类型的临界电流密度。观察到从横向畴壁到涡旋畴壁以及反之的周期性畴壁转变，并且转变机制是通过垂直于线的涡旋核位移发生的。结果表明，非绝热参数β不等于阻尼α，这与最近的理论预测一致。在磁盘中进一步研究了垂直于电流的涡旋核运动，结果表明相反方向的位移可归因于涡旋核的不同极性。
