title: New generation of two-dimensional spintronic systems realized by coupling of Rashba and Dirac fermions.
abstract: Intriguing phenomena and novel physics predicted for two-dimensional (2D) systems formed by electrons in Dirac or Rashba states motivate an active search for new materials or combinations of the already revealed ones. Being very promising ingredients in themselves, interplaying Dirac and Rashba systems can provide a base for next generation of spintronics devices, to a considerable extent, by mixing their striking properties or by improving technically significant characteristics of each other. Here, we demonstrate that in BiTeI@PbSb2Te4 composed of a BiTeI trilayer on top of the topological insulator (TI) PbSb2Te4 weakly- and strongly-coupled Dirac-Rashba hybrid systems are realized. The coupling strength depends on both interface hexagonal stacking and trilayer-stacking order. The weakly-coupled system can serve as a prototype to examine, e.g., plasmonic excitations, frictional drag, spin-polarized transport, and charge-spin separation effect in multilayer helical metals. In the strongly-coupled regime, within ~100 meV energy interval of the bulk TI projected bandgap a helical state substituting for the TI surface state appears. This new state is characterized by a larger momentum, similar velocity, and strong localization within BiTeI. We anticipate that our findings pave the way for designing a new type of spintronics devices based on Rashba-Dirac coupled systems.
authors.affiliation: 1] Institute of Strength Physics and Materials Science, 634021, Tomsk, Russia [2] Tomsk State University, 634050, Tomsk, Russia [3] Donostia International Physics Center (DIPC), 20018 San Sebastián/Donostia, Basque Country, Spain [4] Saint Petersburg State University, Saint Petersburg, 198504, Russia.
authors.forename: Sergey V
authors.initials: SV
authors.lastname: Eremeev
authors.affiliation: 1] Tomsk State University, 634050, Tomsk, Russia [2] Donostia International Physics Center (DIPC), 20018 San Sebastián/Donostia, Basque Country, Spain [3] Saint Petersburg State University, Saint Petersburg, 198504, Russia.
authors.forename: Stepan S
authors.initials: SS
authors.lastname: Tsirkin
authors.affiliation: 1] Tomsk State University, 634050, Tomsk, Russia [2] Donostia International Physics Center (DIPC), 20018 San Sebastián/Donostia, Basque Country, Spain.
authors.forename: Ilya A
authors.initials: IA
authors.lastname: Nechaev
authors.affiliation: 1] Donostia International Physics Center (DIPC), 20018 San Sebastián/Donostia, Basque Country, Spain [2] Departamento de Física de Materiales UPV/EHU, Facultad de Ciencias Químicas, UPV/EHU, Apdo. 1072, 20080 Sebastián/Donostia, Basque Country, Spain [3] Centro de Física de Materiales CFM - MPC, Centro Mixto CSIC-UPV/EHU, 20080 San Sebastián/Donostia, Basque Country, Spain.
authors.forename: Pedro M
authors.initials: PM
authors.lastname: Echenique
authors.affiliation: 1] Tomsk State University, 634050, Tomsk, Russia [2] Donostia International Physics Center (DIPC), 20018 San Sebastián/Donostia, Basque Country, Spain [3] Saint Petersburg State University, Saint Petersburg, 198504, Russia [4] Departamento de Física de Materiales UPV/EHU, Facultad de Ciencias Químicas, UPV/EHU, Apdo. 1072, 20080 Sebastián/Donostia, Basque Country, Spain [5] Centro de Física de Materiales CFM - MPC, Centro Mixto CSIC-UPV/EHU, 20080 San Sebastián/Donostia, Basque Country, Spain.
authors.forename: Evgueni V
authors.initials: EV
authors.lastname: Chulkov