Nuclear magnetic resonance (NMR) and transport measurements have been performed at high magnetic fields and low temperatures in a series of n-type Bi2Se3 crystals. In low density samples, a complete spin polarization of the electronic system is achieved, as observed from the saturation of the isotropic component of the 209Bi NMR shift above a certain magnetic field. The corresponding spin splitting, defined in the phenomenological approach of a 3D electron gas with a large (spin-orbit-induced) effective g-factor, scales as expected with the Fermi energy independently determined by simultaneous transport measurements. Both the effective electronic g-factor and the "contact" hyperfine coupling constant are precisely determined. The magnitude of this latter reveals a non negligible s-character of the electronic wave function at the bottom of the conduction band. Our results show that the bulk electronic spin polarization can be directly probed via NMR and pave the way for future NMR investigations of the electronic states in Bi-based topological insulators.
@article{arxiv.1407.1040,
title = {Hyperfine coupling and spin polarization in the bulk of the topological insulator Bi$_2$Se$_3$},
author = {S. Mukhopadhyay and S. Krämer and H. Mayaffre and H. F. Legg and M. Orlita and C. Berthier and M. Horvatić and G. Martinez and M. Potemski and B. A. Piot and A. Materna and S. Strzelecka and A. Hruban},
journal= {arXiv preprint arXiv:1407.1040},
year = {2015}
}
Comments
Updated version including the supplemental material section. To be published in Rapid Communication, Phys. Rev. B