TY - JOUR

T1 - The dominance of surfaces and interfaces

T2 - A view to magnetoconductance and structure in low-dimensional crystalline films

AU - Pfnür, Herbert

AU - Lükermann, Daniel

AU - Tegenkamp, Christoph

PY - 2012/1/23

Y1 - 2012/1/23

N2 - For ultra-thin films, electronic transport properties at surfaces and interfaces are dominated by electronic scattering at the interfaces. Therefore, as our example with Pb on Si(557) shows, d.c. transport is sensitive to confinement, to growth modes, and to (electronic) surface roughness. During the growth of Pb on Si(557) up to more than 10 monolayers, we found classical and quantum size effects, a pronounced conductance anisotropy and conductance oscillations directly related to the anisotropic layer-by-layer growth mode of the Pb film on this regularly stepped surface. In fact, it turned out that the interface anisotropy, which extends up to the seventh layer in conductance, is kept as a memory effect even for thick (isotropic) layers. By adding a magnetic field, details of the scattering mechanism at impurities and defects are revealed, since elastic, inelastic, spin-orbit scattering contributions can be separated. Strong changes of scattering properties are evident when going from the multilayers to the monolayer, as demonstrated again for the system Pb on Si(557). Contrary to multilayers, spin-orbit scattering dominates for the monolayer, presumably due to the symmetry reduction at the surface and the appearance of spin-split bands split by the Rashba effect. Also the anomaly in spin-orbit scattering close to monolayer completion, coupled with quasi one-dimensional d.c. conductance, can be ascribed to the Rashba effect. The intriguing interplay between bulk and surface conductance with large Rashba split states at the surface is exemplified by a study of multilayer growth of Bi on Si(111). By magnetoconductance we were able to separate bulk from surface contributions. Scattering between strongly spin-polarized Rashba-split states spin can be effectively suppressed, so that only the "classical" magnetoconductance effect remains, as observed in this system.

AB - For ultra-thin films, electronic transport properties at surfaces and interfaces are dominated by electronic scattering at the interfaces. Therefore, as our example with Pb on Si(557) shows, d.c. transport is sensitive to confinement, to growth modes, and to (electronic) surface roughness. During the growth of Pb on Si(557) up to more than 10 monolayers, we found classical and quantum size effects, a pronounced conductance anisotropy and conductance oscillations directly related to the anisotropic layer-by-layer growth mode of the Pb film on this regularly stepped surface. In fact, it turned out that the interface anisotropy, which extends up to the seventh layer in conductance, is kept as a memory effect even for thick (isotropic) layers. By adding a magnetic field, details of the scattering mechanism at impurities and defects are revealed, since elastic, inelastic, spin-orbit scattering contributions can be separated. Strong changes of scattering properties are evident when going from the multilayers to the monolayer, as demonstrated again for the system Pb on Si(557). Contrary to multilayers, spin-orbit scattering dominates for the monolayer, presumably due to the symmetry reduction at the surface and the appearance of spin-split bands split by the Rashba effect. Also the anomaly in spin-orbit scattering close to monolayer completion, coupled with quasi one-dimensional d.c. conductance, can be ascribed to the Rashba effect. The intriguing interplay between bulk and surface conductance with large Rashba split states at the surface is exemplified by a study of multilayer growth of Bi on Si(111). By magnetoconductance we were able to separate bulk from surface contributions. Scattering between strongly spin-polarized Rashba-split states spin can be effectively suppressed, so that only the "classical" magnetoconductance effect remains, as observed in this system.

KW - crystalline films

KW - magnetoconductance

KW - surfaces and interfaces

KW - weak localization

UR - http://www.scopus.com/inward/record.url?scp=84859294936&partnerID=8YFLogxK

U2 - 10.1002/pssa.201127751

DO - 10.1002/pssa.201127751

M3 - Article

AN - SCOPUS:84859294936

VL - 209

SP - 627

EP - 635

JO - Physica Status Solidi (A) Applications and Materials Science

JF - Physica Status Solidi (A) Applications and Materials Science

SN - 1862-6300

IS - 4

ER -