Time-resolved scanning probe microscopy: Investigations and applications of dynamic magnetostriction (invited)

Abstract

We have measured the magnetostrictive response of small nickel and Tb 0.3Dy0.7Fe1.95 cylinders to sudden step changes in applied magnetic field with a time-resolved scanning fiber interferometer. Spatially resolved measurements reveal the nonuniform distortion of the face of the rod as the induced magnetization propagates in toward the center. A crossover is observed, as a function of decreasing cylinder diameter, from eddy current- to longitudinal phonon-limited response times. The ability to characterize dynamic magnetostriction in small samples has also enabled us to perform time-resolved measurements of fast transient signals with a scanning tunneling microscope. Modulation of the tip-sample separation on short time scales is provided by the use of a nickel magnetostrictive tip driven by a local magnetic field coil. The technique offers a broadly applicable means of obtaining fast dynamical information in tunneling microscopy, and is demonstrated here on nanosecond time scales. These experiments illustrate, in the context of magnetics, the general promise of time-resolved scanning probe methods.