Linear-dichroism studies of thin Dy overlayers on Ni(110) and Cu(110) substrates.

In this paper we present polarisation-, temperature-, and thickness-dependent x-ray-absorption measurements on extremely thin Dy overlayers. For Dy overlayers deposited at room temperature on Cu(110) and (magnetic) Ni(110) we observe strong linear clichroism. We deduce that the nature of the dichroic effects is predominantly electrostatic. When Dy is evaporated onto Ni(110) and kept at 50 K almost no dichroism is observed. Deposition of Dy on Cu(110) at 50 K, on the other hand, yields strong clichroism. We discuss these effects in greater detail and formulate a model for the overlayer system that seeks to explain the observed differences