Interplay of topological surface and bulk electronic states in Bi2Se3

Abstract

In this paper we present scanning tunneling microscopy density-ofstates measurements and electronic structure calculations of the

Understanding Bulk Defects in Topological Insulators from Nuclear‐Spin Interactions

“…The observation of metallic surface states often requires minimal bulk defects or compensation for the free carriers. [1][2][3][4][5][6]11,14,37,[38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53] Novel properties have been predicted, such as quantum-Hall-like behavior with quantized conductance of charge and spin in the absence of a magnetic field, and dissipation-less quantum Hall states with time-reversal symmetry (TRS). [11][12][13][14][15][16] First-principles calculations [3,15,16,33,[36][37][38][39][40]48,49,51] and Angle Resolved Photoemission Spectroscopy (ARPES) [5,11,12,39,40,…”

“…Of great interest is the development of local probes of the material's bulk region, which is difficult to interrogate independently from the surface states. [52,53] Here we present a comparative NMR study of the bulk states of multiple TI materials and have relate the results to existing transport and ARPES studies from the literature. The present study confirms that the undesired presence of defects in the bulk state are directly reflected in the NMR parameters.…”

Mapping the 3D surface potential in Bi2Se3

“…Initial studies indicated that theoretical predictions were largely true-topological protection reduces scattering and carriers are helical Dirac-like fermions [4][5][6][7] . However, further investigation raised several issues with its physical and structural properties in actual materials: Bi Se antisites may allow scattering from the surface to the bulk 8,9 , strong band bending creates an additional, topologically trivial, surface state [10][11][12][13] , and deep, unobservable charges may cause fluctuations in the Dirac point 4 .…”

Influence of Doping on the Topological Surface States of Crystalline Bi2Se3 Topological Insulators

“…Therefore, high quality p-type crystals are critically important for basic as well as applied research on Bi 2 Se 3 , and a great deal of research work has been devoted to manipulating the Fermi level by searching for suitable p-type dopants. These efforts include volumetric doping with elements, such as Mn [ 10 ], Sn [ 4 ], Fe [ 11 , 12 ], Ca [ 13 , 14 ], Mg [ 15 ], Cr [ 16 , 17 ], Pb [ 18 ], surface adsorption with Fe [ 19 , 20 ], Co [ 21 ], and controlling a number of native anti-site defects [ 22 , 23 , 24 ]. Doping with magnetic materials is particularly important due to the fact that the magnetic order leads to the breaking of the time reversal symmetry, and thus, can destroy the topological order.…”