Obtaining giant Rashba–Dresselhaus spin splitting in two-dimensional chiral metal–organic frameworks

Abstract

Two-dimensional (2D) nonmagnetic semiconductors with large Rashba–Dresselhaus (R–D) spin splitting at valence or conduction bands are attractive for magnetic-field-free spintronic applications. However, so far, the number of 2D R–D inorganic semiconductors has been quite limited, and the factors that determine R–D spin splitting as well as rational design of giant spin splitting, remain unclear. For this purpose, by exploiting 2D chiral metal–organic frameworks (CMOFs) as a platform, we theoretically develop a three-step screening method to obtain a series of candidate 2D R–D semiconductors with valence band spin splitting up to 97.2 meV and corresponding R–D coupling constants up to 1.37 eV Å. Interestingly, the valence band spin texture is reversible by flipping the chirality of CMOFs. Furthermore, five keys for obtaining giant R–D spin splitting in 2D CMOFs are successfully identified: (i) chirality, (ii) large spin–orbit coupling, (iii) narrow band gap, (iv) valence and conduction bands having the same symmetry at the Γ point, and (v) strong ligand field.