Massive Dirac Fermions and Strong Shubnikov-de Haas Oscillations in Topological Insulator Sm,Fe:Bi2Se3 Single Crystals

TL;DR

This study demonstrates that co-doping Bi2Se3 topological insulators with rare-earth Sm and transition-metal Fe induces ferromagnetism, opens a surface Dirac gap, and exhibits strong quantum oscillations, advancing quantum device applications.

Contribution

It introduces a novel co-doping strategy with Sm and Fe in Bi2Se3, combining benefits of both dopants to enhance magnetic and electronic properties for quantum effects.

Findings

Ferromagnetic ordering observed in co-doped crystals

Surface Dirac gap of 44 meV confirmed by spectroscopy

Ultra-strong Shubnikov-de Haas oscillations detected

Abstract

Topological insulators (TIs) are emergent materials with unique band structure, which allow the study of quantum effect in solids, as well as contribute to high performance quantum devices. To achieve the better performance of TI, here we present a co-doping strategy using synergistic rare-earth Sm and transition-metal Fe dopants in Bi2Se3 single crystals, which combine the advantages of both transition metal doped TI (high ferromagnetic ordering temperature and observed QAHE), and rare-earth doped TI (large magnetic moments and significant spin orbit coupling). In the as-grown single crystals, clear evidences of ferromagnetic ordering were observed. The angle resolve photoemission spectroscopy indicate the ferromagnetism opens a 44 meV band gap at surface Dirac point. Moreover, the carrier mobility at 3 K is ~ 7400 cm2/Vs, and we thus observed an ultra-strong Shubnikov-de Haas oscillation in the longitudinal resistivity, as well as the Hall steps in transverse resistivity below 14 T. Our transport and angular resolved photoemission spectroscopy results suggest that the rare-earth and transition metal co-doping in Bi2Se3 system is a promising avenue implement the quantum anomalous Hall effect, as well as harnessing the massive Dirac fermion in electrical devices.