Spin-polarization of topological crystalline and normal insulator Pb${}_{1-x}$Sn${}_x$Se (111) epilayers probed by photoelectron spectroscopy

Abstract

The helical spin texture on the surface of topological crystalline insulators (TCI) makes these materials attractive for application in spintronics. In this work, spin-polarization and electronic structure of surface states of (111)-oriented Pb${}_{1-x}$Sn${}_x$Se TCI epitaxial films are examined by angle -- as well as spin-resolved photoemission spectroscopy (SR-ARPES). High-quality epilayers with various Sn content are grown by the molecular beam epitaxy (MBE) method. Topological-normal insulator transition manifesting itself as band gap opening is observed. It is shown that the gap opening can be induced not only by changing the Sn content of the epilayer but also depositing a transition metal (TM) on its surface. In the latter case, the observed gaping of the surface states is caused by change in surface composition and not by magnetism. We also show that helical spin polarization is present not only for samples of topological composition but also for trivial ones (with an open band gap). The observed spin polarization reaches a value of 30 % for the in-plane spin component and is almost absent for the out-of-plane one. We believe that our work will pave the way for the application of surface states not only of topological but also normal insulators based on lead-tin chalcogenides in spin-charge conversion devices.

9 pages, 7 figures; Accepted version

References in corpus (8)

• Quantum Spin Hall Effect and Topological Phase Transition in HgTe Quantum Wells
• Non-Abelian Anyons and Topological Quantum Computation
• Quantum Spin Hall Insulator State in HgTe Quantum Wells
• Topological Crystalline Insulators
• Surface state dominated spin-charge current conversion in topological insulator/ferromagnetic insulator heterostructures
• Spin-Polarized Surface Resonances Accompanying Topological Surface State Formation
• Spin-polarized (001) surface states of the topological crystalline insulator Pb_{0.73}Sn_{0.27}Se
• Unconventional transformation of spin Dirac phase across a topological quantum phase transition