Exchange coupling in the correlated electronic states of amorphous GdFe films

Abstract

The bulk sensitivity of hard x-ray photoelectron spectroscopy in combination with circularly polarized radiation of the P09 beamline at PETRA III enables the investigation of the magnetic properties of capped films. We have determined the temperature dependence of the magnetic circular dichroism in the Fe 2p and in the Gd 3d states in amorphous GdFe films. The magnetic dichroism reflects the stronger temperature dependence of Gd moments compared to Fe moments in agreement with mean-field models. We resolved the exchange split Gd 3d(5/2) substates and found a significant temperature dependence of the splitting which is attributed to a temperature dependent part of the exchange energy caused by Stoner-like itinerant states. A comparison of experimental and simulated x-ray photoemission spectra with corresponding data for x-ray absorption spectroscopy exciting the identical core holes clearly demonstrates that the core hole exchange interaction is the origin of the observed multiplet features for Gd.