Designing the Rashba spin texture by adsorption of inorganic molecules

Rico Friedrich,Vasile Caciuc,Nicolae Atodiresei,Gustav Bihlmayer,Stefan Blügel

doi:10.1088/1367-2630/aa64a1

Abstract

Using the physisorption and chemisorption of inorganic molecules on BiAg2/Ag(111) we demonstrate from first principles that the spin–orbit splitting and the spin direction of surface Rashba-split states can be manipulated selectively. Although NH3 is physisorbed, it nevertheless leads to a slight enhancement of the outward buckling of the surface Bi that increases the magnitude of the Rashba splitting. On the other hand, the weakly chemisorbed BH3 determines a strong inward relaxation of the surface Bi such that the occupied Rashba state shifts into Ag bulk states while a new unoccupied one is induced. Importantly, for the BH3–BiAg2/Ag(111) system the size of the out-of-plane spin polarization is significantly larger than the in-plane one at variance with the clean surface case.

Highlights

In this respect, the spin–orbit coupling (SOC) plays a crucial role to manipulate the spin degree of freedom in spintronics [7]
It was shown that a graphene layer on the Ir(111) surface protects the Rashba-split surface state from air [29] and keeps kSO unaffected even when Au nanoclusters are deposited on the graphene layer [30], demonstrating that the 2DEG of the surface state can be isolated in a well-defined state
For the cobalt phthalocyanine (CoPc)/Bi2Se3 system a recent angle resolved photo emission spectroscopy (ARPES) study demonstrated that the topological surface state is not present anymore in the first quintuple layer due to the molecule–surface hybridization, but it is buried in the second quintuple layer [34]

Summary

Introduction

The spin–orbit coupling (SOC) plays a crucial role to manipulate the spin degree of freedom in spintronics [7]. A important effect induced by both molecules on the BiAg2/Ag(111) surface is the structural change upon molecular adsorption, namely how BH3 and NH3 modify the magnitude of the outward relaxation of the surface Bi atom, dBi. Despite of the weak interaction of NH3 with this substrate, Bi is slightly pulled out of surface by about 10% leading to dBNiH3 = 0.67 Å with respect to the clean surface buckling of 0.61 Å.

Objectives

Results

Conclusion