Orbital-Driven Rashba Effect in a Binary Honeycomb Monolayer AgTe
M. Ünzelmann, Hendrik Bentmann, Philipp Eck, Tilman Kißlinger, B. Geldiyev, Janek Rieger, Simon Moser, Raphael C. Vidal, K. Kißner, Lutz Hammer, M. Alexander Schneider, Thomas Fauster, Giorgio Sangiovanni, Domenico Di Sante, F. Reinert
Abstract
The Rashba effect is fundamental to the physics of two-dimensional electron systems and underlies a variety of spintronic phenomena. It has been proposed that the formation of Rashba-type spin splittings originates microscopically from the existence of orbital angular momentum (OAM) in the Bloch wave functions. Here, we present detailed experimental evidence for this OAM-based origin of the Rashba effect by angle-resolved photoemission (ARPES) and two-photon photoemission experiments for a monolayer AgTe on Ag(111). Using quantitative low-energy electron diffraction analysis, we determine the structural parameters and the stacking of the honeycomb overlayer with picometer precision. Based on an orbital-symmetry analysis in ARPES and supported by first-principles calculations, we unequivocally relate the presence and absence of Rashba-type spin splittings in different bands of AgTe to the existence of OAM.