ELFT HÍRADÓ

[tcsaba <tcsaba AT eik.bme.hu>]

                     M E G H Í V Ó - I N V I T A T I O N

      Seminar Series of the Department of Theoretical Physics at the
            Budapest University of Technology and Economics


                          Balazs Ujfalussy
               (Wigner Research Centre for Physics)

   First-principles theory of superconducting heterostructures


We show how Multiple Scattering Theory can be generalized to
solve the Kohn-Sham-Bogoliubov-de Gennes equations for surfaces
of supeconductors and their interfaces with normal metals. The
theory is than applied to various overlayers where we show that
in the energy range of the superconducting gap, the
quasiparticle spectrum consists of Andreev bound states with a
dispersion which is closely connected to the underlying
electronic structure of the overlayer. We also find that the
spectrum has a strongly k-dependent induced gap. In the case of
thick superconducting layers we calculate the critical temperature
based on the thickness dependence of the gap size and we compare
it with with experiments on Au/Nb(100). In the case of thin
superconductor layers, where the electron-phonon interaction may
change significantly, we also calculate the layer dependent phonon
spectrum to determine the layer dependence of the electron-phonon
coupling. The theory is applied to niobium slabs and thin niobium-gold
multilayers, where we investigate both the critical temperature and
the inverse proximity effect observed in thin superconducting
heterostructures.


Idöpont: 2016. március 18. péntek, 10:15
Helyszín: BME Fizikai Intézet, Elméleti Fizika Tanszék,
Budafoki út 8. F-épület, III lépcsöház, szemináriumi szoba