Limits of validity of the Rashba model in BiTeI: High-field magneto-optical study

S. Bordács , M. Orlita (1) , M. Šikula , H. Murakawa , Y. Tokura

1 LNCMI-G - Laboratoire national des champs magnétiques intenses - Grenoble

It was recently shown that BiTeI, a semiconductor with polar crystal structure, possesses a giant spin splitting of electrons, which has been interpreted in terms of Rashba-type spin-orbit coupling. Here we use high field magneto-optical spectroscopy to quantify the deviations of the conduction-band profile from this appealing, but at the same time, strongly simplifying model. We find that the optical response-comprising a series of inter-Landau level excitations-can be described by the Rashba model only at low magnetic fields. In contrast, the high-field response appears to be more consistent with a simple picture of massless electrons in a conical band. This points towards more linear rather than parabolic dispersion at energies well above the bottom of the conduction band.

Domaines: Physique [physics]; Matière Condensée [cond-mat]

S. Bordács, M. Orlita, M. Šikula, H. Murakawa, Y. Tokura. Limits of validity of the Rashba model in BiTeI: High-field magneto-optical study. Physical Review B: Condensed Matter and Materials Physics (1998-2015), 2019, 100 (15), ⟨10.1103/PhysRevB.100.155203⟩. ⟨hal-02324530⟩