Observation of a Ferromagnetic-to-Paramagnetic Phase Transition on a Ferromagnetic Surface Using Spin-Polarized Photoelectron Diffraction: Gd(0001)

Abstract

The ferromagnetic system Gd(0001) has been studied by spin-polarized photoelectron diffraction, using the highly spin-polarized $^{7}S$ and $^{9}S$ multiplet peaks in Gd $4s$ and $5s$ spectra. Temperature-dependent spin asymmetries derived from the $^{7}S$-to- $^{9}S$ peak intensity ratios exhibit pronounced changes over a range of temperatures spanning both the bulk Curie temperature ${T}_{\mathrm{cb}}$ and a surface transition temperature ${T}_{\mathrm{cs}}$ that is found to be $\ensuremath{\approx}85\mathrm{K}$ above ${T}_{\mathrm{cb}}$. The surface transition also appears to span several atomic layers.