Magnetism and quantum-size effects of thin FCC films

Abstract

The magnetism and the electronic structure of ultrathin FCC(100) transition metal films of Fe, Co, and Ni, as well as quantum-size and magnetic effects in thin Cu overlayers on these films have been investigated by spin- and angle-resolved photoemission. The electronic structure of FCC Co(100) films displays exchange split states with a typical exchange splitting of 1.5-1.6 eV near #GAMMA#. Magnetic surface states are observed in FCC Ni(100) with an exchange splitting of about 0.2 eV. These states are in good agreement with ab initio slab calculations. In thin FCC Fe films on Cu(100) and Co(100) two distinct regions in the magnetism and electronic structure are observed as a function of Fe film thickness. The first phase corresponds to a ferromagnetic high-spin phase with large magnetic moments. The second phase displays a magnetically alive surface region with strongly exchange split electronic states and thus large magnetic moments. The film interior of this second phase consist of local moments, which are reduced in comparison to the magnetic moments of the surface and do not display a long range magnetic order above 100 K. The experimental results agree well with corresponding ab initio calculations. Discrete spin-polarized sp-like states, which can be described in the framework of quantum well (QW) states, are investigated in Cu(100) overlayers on FCC Fe, Co, and Ni films. Both sp-like and d-like QW states are observed. Depending on the substrate, both intensity and binding energy changes of the Cu QW states are observed, which are in excellent agreement with ab initio calculations. For Cu on Co(100) the QW states that are responsible for both the long and the short coupling period in the interlayer exchange coupling across Cu(100) spacers are found. Thus a firm relation between the spin-polarized QW states and the oscillatory interlayer coupling is established. (orig.)162 refs.Available from TIB Hannover: RA 831(3503) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman