Ultrafast magnetization dynamics probed by anisotropic magnetoresistance

The authors use time resolved measurements of the anisotropic magnetoresistance (AMR) to study ultrafast magnetization dynamics of microstructured disks of Permalloy. The devices show an AMR of the order of 0.25% revealing the characteristic cos(2) angular dependence. From the time resolved AMR the authors derive the in plane angular excursion of the magnetization with angular resolution down to 1 degrees. From the decay of the homogeneous precession the authors derive a Gilbert damping parameter of 0.008 +/- 0.001. This technique can be applied to study magnetization precession and damping in individual micropatterned devices of a wide variety of magnetic thin film and multilayer materials. (c) 2007 American Institute of Physics.