Paper SS2-TuM13
A Photoelectron Diffraction Study of Cu₃Mn(100)

Tuesday, October 16, 2007, 12:00 pm, Room 611

In the Angstrom to nanoscale regime where electronic localisation blurs to itinerant behaviour, magnetic phenomena become highly dependent on dimensionality and local environment. Magnetic exchange between two different magnetic phases is one such phenomenon that is affected when dimensions are reduced to the nanoscale. We are specifically interested in studying the exchange properties at the interface of an antiferromagnetic or ferromagnetic material and a spin glass surface. Our first task however is to fully understand a spin-glass surface by mapping out the surface and bulk band structure as well as determine the surface crystalline structure. We have chosen the CuMn system because it represents a model spin-glass whose transition temperature is easily attainable. The bulk phase-diagram for the CuMn system displays a face-centered-cubic phase at room temperature for atomic percent concentrations of Mn from 0 to ~25% and the spin-glass transition temperature for CuMn in this percentage region increases linearly to ~110K at 25%at. Mn. We present here synchrotron-based azimuthal-scanned photoelectron diffraction measurements using the Cu and Mn 3p-orbitals from a Cu₃Mn(100) surface and compare them to simulation and to corresponding data sets for Cu(100). The number of Mn-atoms in the upper-most layer is lower than expected from a truncated bulk surface suggesting surface segregation or oscillatory behaviour. Details of surface reconstruction and near-surface relaxation will be presented.