Bulk and surface ion-electron emission at the Curie point from nickel

Energy spectra of electrons emitted from a nickel target under 5 keV He+ ion bombardment were examined. The typical energy spectrum consists of the background, which is connected with bulk electrons (bulk ion-electron emission) and of a number of peaks, which correspond to adsorbed and contaminant particles. The escape of these electrons takes place with the participation of the excited surface atoms (oxygen, nitrogen etc.) and the metal surface electrons (surface ion-electron emission). Increasing the target temperature influences the yield of the bulk and surface electrons, this effect can be noticed especially near the Curie temperature. The temperature dependence of the bulk emission from nickel shows a distinct increase near the Curie point. This result has been presented elsewhere. We can conclude that the surface mechamism of electron creation also depends on the magnetic properties of the target and is independent of the ion bombardment, the Curie temperature for bulk and surface is the same. Above the Curie point the system of peaks shifts to the high energy region and the areas of the peaks increase. Lack of the exchange above the Curie temperature releases the electrons from the 3d band, which can participate in the surface mechanism of electron creation. (orig.)