Tuning of the Rashba effect in Pb quantum well states via a variable Schottky barrier

Abstract

Spin-orbit interaction (SOI) in low-dimensional systems results in the fascinating property of spin-momentum locking. In a Rashba system the inversion symmetry normal to the plane of a two-dimensional (2D) electron gas is broken, generating a Fermi surface spin texture reminiscent of spin vortices of different radii which can be exploited in spin-based devices. Crucial for any application is the possibility to tune the momentum splitting through an external parameter. Here we show that in Pb quantum well states (QWS) the Rashba splitting depends on the Si substrate doping. Our results imply a doping dependence of the Schottky barrier which shifts the Si valence band relative to the QWS. A similar shift can be achieved by an external gate voltage or ultra-short laser pulses, opening up the possibility of terahertz spintronics.

Spin-resolved band structure of a densely packed Pb monolayer on Si(111)

“…The value of the total carrier concentration of n ≈ 2.73×10 14 cm −2 is in perfect agreement with the value deduced from the calculated band structure [12,13]. Compared to the Pb-adatom density of 1.04×10 15 cm −2 ( 4 3 ML phase), every Pb atom within the ( √ 3× √ 3) unit cell donates 1 4 electron into the metallic S1 state. Similarly to the Tl/Si(111) system [26] we assume that only the Pb6p 2 electrons are involved in the bonding formation.…”

“…Since many of these adlayers exhibiting the mentioned phenomena are built from heavy-Z elements, spin-orbit coupling * tegenkamp@fkp.uni-hannover.de becomes important, as illustrated by a controllable Rashbatype spin splitting [14,15], and reveals new exotic quantum phenomena, e.g., magnetically ordered phases in frustrated 2D systems [16] or strongly correlated spin-orbit entangled states, as recently shown for the quasi-1D DS phase of 1.31 ML Pb/Si(557) [17] by spin-and angle-resolved photoemission spectroscopy (SARPES) [18].…”

Entanglement and manipulation of the magnetic and spin–orbit order in multiferroic Rashba semiconductors

“…The larger the symmetry breaking, the larger the Rashba spin splitting becomes151617. This is exemplified by the giant spin splitting observed for the polar semiconductor BiTeI (refs 18, 19), the polar surface of SrTiO 3 (ref.…”

Spin polarization of surface states on W(1 1 0): Combined influence of spin–orbit interaction and hybridization

“…Rashba systems and topological insulators stimulate strong demand for direct observation of their band structure with separation of spin-up and -down states. Spinand angle-resolved photoemission spectroscopy (spin-ARPES) and inverse photoemission are the ideal tools to directly observe the spin-polarized electronic band structures, as demonstrated for noble metal surfaces [5,6], heavy metal atoms on semiconductor [7][8][9][10][11][12][13] and surface alloys [14,15].…”