The Observation of Spin-Polarized Wavevectors spanning the Fermi Surface of Magnetic Nanostructures

We report angle-resolved photoemission measurements of changes in the electronic structure with changing composition of pseudomorphic films of FeNi magnetic alloys grown epitaxially on Cu(001). The measurements show that the sp-band is a prominent feature of the Fermi surface throughout k-space for all of the alloys and the magnetic 3d pseudomorphic fcc films. A band-structure calculation of Ni allows us to identify d-hole pockets which increase in size with changing stoichiometry. Minority spin states highlite specific regions of k-space associated with key spanning vectors that determine the oscillatory exchange coupling which underpins the giant magnetoresistance (GMR) effect in heterostructures