Spin-polarized scanning tunneling microscopy on ferromagnets

A straightforward approach to spin-polarized scanning tunneling microscopy based on the magnetotunnel effect between a ferromagnetic tip and a ferroma gnetic sample is demonstrated. By periodically changing the magnetization o f the tip in combination with a lock-in technique, topographic and spin-dep endent parts of the tunnel current are separated and the topography and the magnetic structure of the sample are recorded simultaneously. Results are given for polycrystalline Ni and single crystalline Co(0001) surfaces, reve aling a high spin contrast, low data acquisition times, and a resolution do wn to 10 nm. Potentials and limitations of this technique are discussed. (C ) 1999 American Institute of Physics. [S0003-6951(99)00439-8].