STRONG TEMPERATURE DEPENDENCE OF FERROMAGNETISM AT Ni and Tb SURFACES DETERMINED WITH ELECTRON CAPTURE SPECTROSCOPY ECS*

The magnetic structure of the topmost atomic layer of Ni and Tb surface has been investigated using electron capture spectroscopy (ECS). Contrary to bulk behavior, at Ni(ll1) surfaces, the long-range magnetic order, characterized by the long-range electron spin polarization (ESP), decreases from-43 % at T = 293 K almost linearly to zero at the bulk Curie temperature T,, = 631 K. The “local ” surface magnetic order (SMO) at Ni(ll1) surfaces is temperature independent and is detected far above Tc,. At Tb surfaces, however, the “local ” SMO is strongly temperature dependent and disappears above Tcb. 1. Introduction the spin-spin-correlation length diverges causing sur-face effects to extend deep into the bulk. At present there is an increasing scientific and tech- In this paper we report on the temperature depen-nological interest in a deeper comprehension of fer- dence of the long-range and “local ” surface magnetic romagnetism in connection with surfaces. Rapid order for Ni which is the prototype of an itineran