Tuning chemical potential in the dirac cone by compositional engineering

R K Gopal,Chiranjib Mitra,Sourabh Singh,Jit Sarkar

doi:10.1063/1.4999254

Abstract

To realize fully topological transport for any device applications it is essential to tune the chemical potential in the bulk gap of the Dirac cone. Bi2Se3 (BS) and Bi2Te3 (BT) thin films do not show in general topological transport as the chemical potential doesn’t lie entirely in the bulk gap. We report the successful formation of bulk insulating ternary topological insulators Bi2Se2Te (BST) by double target pulsed laser deposition technique. The films were deposited with sequential ablation of separate BS and BT targets. From the X-ray diffraction analysis and temperature dependent resistivity, we were able to conclude that the as-grown thin films have ordered chalcogen layers and the chemical potential in these thin films lie in the bulk gap. We have been able to achieve this fully topological transport in our sample grown by this technique. Our Magnetotransport data exhibits pronounced two-dimensional weak-antilocalization behavior (WAL) at low temperatures. It was possible to tune the chemical potential at will in the gap by depositing thin films through pulsed laser deposition technique using this simple and cost effective double target approach to grow quaternary TI thin films.

Highlights

Three-dimensional topological insulators (TI) exhibit a unique state of quantum matter with insulating bulk and gapless metallic surface states protected by the Z2 topology of the bulk.[1,2] Linear energy-momentum dispersion and large Fermi velocity of these surface electrons provide them with the name Dirac electrons
After characterizing our thin films with all the necessary tools, we focus our attention towards the transport properties of the BST thin films
The R–T data of the sample PS2 displays a fully metallic character down to 25 K and shows an insulating ground state due to the competing effects of freezing of the bulk electronic states and electron-electron interaction. This suggests that the chemical potential of PS2 thin film lies in the bulk conduction band which is consistent with the ARPES studies and recent transport studies on single crystals of this composition.[7,23,24]

Summary

Tuning chemical potential in the dirac cone by compositional engineering

Cite as: AIP Advances 7, 105112 (2017); https://doi.org/10.1063/1.4999254 Submitted: 20 July 2016 • Accepted: 05 October 2017 • Published Online: 20 October 2017 R. K. Gopal, Sourabh Singh, Jit Sarkar, et al. ARTICLES YOU MAY BE INTERESTED IN Weak-antilocalization and surface dominated transport in topological insulator Bi2Se2Te AIP Advances 5, 047111 (2015); https://doi.org/10.1063/1.4917455 Surface optical and bulk acoustic phonons in the topological insulator, Bi2Se2Te Applied Physics Letters 106, 241106 (2015); https://doi.org/10.1063/1.4922641 The quantum spin Hall effect and topological insulators Physics Today 63, 33 (2010); https://doi.org/10.1063/1.3293411 R. K. Gopal, Sourabh Singh, Jit Sarkar, and Chiranjib Mitraa Indian Institute of Science Education and Research Kolkata, Mohanpur 741 246, India (Received 20 July 2016; accepted 5 October 2017; published online 20 October 2017)

INTRODUCTION

RAMAN AND XRD ANALYSIS

TRANSPORT PROPERTIES

Bφ B

CONCLUSION