Regensburg 2019 – wissenschaftliches Programm
TT 35.5: Vortrag
Dienstag, 2. April 2019, 15:00–15:15, H23
Magnetoconductance in Bi quantum well states: coupling of interfaces — •Doaa Abdelbarey and Herbert Pfnür — Institut für Festkörperphysik, Leibniz Universität Hannover
Ultrathin epitaxial Bi films are governed by strongly spin-polarized bands that determine to a large extent their magneto-transport properties. Magneto-conductance of films grown epitaxially on Si(111) with a thickness of 10 to 100 bilayers (BL) was measured mostly at T= 8 K in magnetic fields up to 4T and with orientations both perpendicular and parallel to the surface plane. For B-fields normal to the surface weak anti-localization (WAL) was observed. Analysis within the theory by Hikami et al.  indicates strong coupling of the interfaces up to 50 BL, whereas above 80 BL two independently conducting channels were observed.
For the in-plane B-field orientation, the magneto conductivity turned out to be anisotropic. Whereas for in-plane B-fields parallel to the current direction and for films up to 70 BL mainly weak localization is seen, it switches to WAL for larger thicknesses. For in-plane B-fields perpendicular to the current only WAL was observed irrespective of thickness. Both curves merge close to 100 BL, i.e. WAL becomes independent of B-field direction. These phenomena are explained within the framework of interface scattering, including superimposed effects of band structure and spin polarization due to the Rashba effect.
Hikami S., et al., Prog. Theor. Phys. 63, 707 (1980)