Temperature-dependent surface magnetization of FeNi3(111) studied by spin-resolved appearance potential spectroscopy

The temperature-dependent magnetic properties of the: FeNi3(lll) surface were investigated by means of spin-resolved appearance potential spectroscopy. Within the: temp erature range studied, from LOO K to 1100 K, two phase transitions occur in the built: a compositional: order-disorder phase transition between 770 and 785 K and a ferromagnetic-paramagnetic phase transition with a Curie temperature of 863 K. The first one does not show up in the appearance potential signals of Fe and Ni, while the latter is reflected in the spin-asymmetry signals; Both the Fe and the Ni signals follow the bulk magnetization curve of FeNi3 with no evidence of any exceptional surface magnetic properties. Furthermore our data show that; to a good approximation, the spin asymmetry of the appearance potential signal is proportional to the magnetization.