Density inhomogeneities and Rashba spin-orbit coupling interplay in oxide interfaces. (May 2019)

• Record Type: Journal Article
• Authors: Bovenzi, N.; Caprara, S.; Grilli, M.; Raimondi, R.; Scopigno, N.; Seibold, G.
• Is Part Of: Journal of physics and chemistry of solids. Volume 128(2019)
• Page Start: 118
• Page End: 129
• Publication Date: 2019-05
• Subjects: Solids -- Periodicals; Solides -- Périodiques; Solids; Periodicals; 530.41
• DOI: 10.1016/j.jpcs.2017.09.013
• Languages: English
• ISSNs: 0022-3697

Abstract

Abstract: There is steadily increasing evidence that the two-dimensional electron gas (2DEG) formed at the interface of some insulating oxides like LaAlO3 /SrTiO3 and LaTiO3 /SrTiO3 is strongly inhomogeneous. The inhomogeneous distribution of electron density is accompanied by an inhomogeneous distribution of the (self-consistent) electric field confining the electrons at the interface. In turn this inhomogeneous transverse electric field induces an inhomogeneous Rashba spin-orbit coupling (RSOC). After an introductory summary on two mechanisms possibly giving rise to an electronic phase separation accounting for the above inhomogeneity, we introduce a phenomenological model to describe the density-dependent RSOC and its consequences. Besides being itself a possible source of inhomogeneity or charge-density waves, the density-dependent RSOC gives rise to interesting physical effects like the occurrence of inhomogeneous spin-current distributions and inhomogeneous quantum-Hall states with chiral "edge" states taking place in the bulk of the 2DEG. The inhomogeneous RSOC can also be exploited for spintronic devices since it can be used to produce a disorder-robust spin Hall effect. Highlights: The evidences of inhomogeneity in oxide interfaces and two mechanisms generating an electronic phase separation are reviewed. The model of Rashba spin-orbit coupling (RSOC) depending on the local electron density is introduced as a mechanism of electronic phase separation. The density-dependent RSOC generating inhomogeneous Quantum Hall States is explored. The possibility of exploiting an inhomogeneous RSOC to generate a robust spin-Hall effect is discussed.