RECENT DEVELOPMENTS IN SURFACE AND THIN-FILM MAGNETISM PROBED BY SPIN-POLARIZED ELECTRONS

Experiments using spin-polarized low-energy electrons provide direct access to surface magnetic properties by separately probing the exchange-split majority and minority electronic states to an information depth of just a few atomic layers. This is demonstrated by results from two types of experiments. (i) Magnetometry with secondary electrons gives information on the magnetization as a function of the field and temperature as well as on the exchange coupling at a ferromagnetic surface or between ultrathin magnetic films. (ii) Spin- and angular-resolved inverse photoemission allows detailed study of the spin-dependent empty electronic structure, thereby complementing information gained by photoemission on the occupied states. Results on energy versus momentum dispersion, exchange splitting of bulk and surface states, and adsorbate-induced changes of the spin-dependent electronic structure contribute to a microscopic picture of ferromagnetism at surfaces. The spin dependence of interface states is important for understanding magnetic coupling phenomena in thin film structures.