title: Landau level spectroscopy of Dirac electrons in a polar semiconductor with giant Rashba spin splitting.
abstract: Optical excitations of BiTeI with large Rashba spin splitting have been studied in an external magnetic field (B) applied parallel to the polar axis. A sequence of transitions between the Landau levels (LLs), whose energies are in proportion to √B were observed, being characteristic of massless Dirac electrons. The large separation energy between the LLs makes it possible to detect the strongest cyclotron resonance even at room temperature in moderate fields. Unlike in 2D Dirac systems, the magnetic field induced rearrangement of the conductivity spectrum is directly observed.
authors.affiliation: Quantum Phase Electronics Center and Department of Applied Physics, University of Tokyo, Tokyo 113-8656, Japan.
authors.forename: Sándor
authors.initials: S
authors.lastname: Bordács
authors.forename: Joseph G
authors.initials: JG
authors.lastname: Checkelsky
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Murakawa
authors.forename: Harold Y
authors.initials: HY
authors.lastname: Hwang
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Tokura