First observation of a ferromagnetic-to-paramagnetic phase transition on a ferromagnetic surface using spin-polarized photoelectron diffraction

Abstract

Spin-polarized photoelectron diffraction (SPPD) has been used previously by the authors group to study two antiferromagnetic surfaces (KMnF{sub 3} (011) and MnO(001)) - these measurements provided evidence of a surface and/or short-range-order magnetic transition significantly above the bulk transition temperature. The authors here report the first use of SPPD to study the order-disorder transitions on a ferromagnetic surface: Gd(0001). Prior work on Gd(0001) suggests that it is unusual in having a surface transition temperature that is 20-60 K above the bulk transition temperature, but there is still not total agreement on the existence of this effect and its origins. The authors have thus used the multiplet-split Gd 4s and Gd 5s photoelectron spectra as sources of spin-polarized photoelectrons to study this magnetic transition.