ON POSSIBILITY OF SPIN-POLARIZED ATOMIC-FORCE MICROSCOPY

A possible way of realizing an atomic force microscope with spin-resolving properties is analysed. A model is furnished where the tip of the microscope is made up of a semiconductor in which the electron spins are oriented by interband absorption of circularly polarized light. It is shown by using a time-dependent perturbation theory that a spin-dependent force will appear between the tip and the surface of a ferromagnetic sample. This force is caused by tunneling splitting of the electronic levels of the tip and the sample. Its magnitude is estimated to be of the order of 1-10 pN. A principle of practical operation and some applications of spin-sensitive atomic force microscopes are discussed.