Effect of adsorbed magnetic and non‐magnetic atoms on electronic transport through surfaces with strong spin‐orbit coupling

Abstract

Adsorption‐induced reduction of the surface state conductivity in epitaxial Bi(111) films, a prototype system with a large Rashba‐induced surface state splitting by adsorbed atoms of Bi, Fe and Co was investigated by macroscopic surface magneto‐transport measurements at a temperature of 10 K. A detailed analysis of magneto‐transport, DC‐transport and Hall data reveals that the scattering efficiencies for Co and Fe are by a factor of two larger than for Bi. While for the latter, charge transfer and change of band filling near the Fermi level is negligible, we found an increase of hole concentration upon Co and Fe adsorption. These atoms act as acceptors and retract roughly 0.5 electrons from the surface per adsorbed atom. Besides the dominant classical magneto‐conductance signal the films show signatures of weak anti‐localization (WAL) reflecting the strong spin‐orbit coupling in Bi(111) surface states. Our measurements show that the control of hybridization is important in order to make use of local spin‐moments and to increase the backscattering rate in strongly spin‐orbit coupled systems, e. g., topological insulators.

Electronic properties of bismuth nanostructures

“…Although the transition into the semiconducting regime offers great potential for applications [20,21], it is still subject to an ongoing debate and the growing importance of surface states with increasing surface-to-volume ratio in very thin films has to be considered. The surface state conductivity of Bi(1 1 1) films has been found to be particularly large and in recent years various transport measurements [22][23][24][25][26][27][28], and magnetotransport measurements [29][30][31] suggested that the conductivity of thin films is composed of two channels, i.e. a semiconducting and a metallic contribution, ascribed to the film interior and surface.…”

Structural modification of thin Bi(1 1 1) films by passivation and native oxide model

“…Semiconductor-like behavior was confirmed by measurements of the temperature dependent conductivity, e.g., in Refs. [4][5][6][7][8][9]. The expected quantum confinement relies on the assumption that the crystal structure in the nanoscale system does not change considerably compared to the bulk and that there are no conducting surface states.…”