K Absorption Edge Magnetic Circular-X-Ray Dichroism of Fe-Ni Alloys

We report Magnetic Circular X-ray Dichroism (MCXD) measurements in Fe-Ni alloys. We used an energy dispersive beamline in our measurements. A polychromator spectrum contains self reference both in intensity and energy since all energies are measured at the same time and remain stable during an energy scan since no movement of the X-ray optics is necessary. We measured the K absorption edges in Fe and Ni (s - p electronic states) in the à ferromagnetic alloys of Fe-Ni. We observe that the signal at the invar composition is of comparable strengh as other compositions in contrast to previous studies. We used cold rolled (disordered) foils instead of powders. The measurements reveal changes of the MCXD signal with composition and crystal structure