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Title: Distinct effects of Cr bulk doping and surface deposition on the chemical environment and electronic structure of the topological insulator Bi 2 Se 3

In this report, it is shown that Cr doped into the bulk and Cr deposited on the surface of Bi2Se3 films produced by molecular beam epitaxy (MBE) have strikingly different effects on both the electronic structure and chemical environment. Angle resolved photoemission spectroscopy (ARPES) shows that Cr doped into the bulk opens a surface state energy gap which can be seen at room temperature; much higher than the measured ferromagnetic transition temperature of ≈ 10 K. On the other hand, similar ARPES measurements show that the surface states remain gapless down to 15 K for films with Cr surface deposition. In addition, core-level photoemission spectroscopy of the Bi 5d, Se 3d, and Cr 3p core levels show distinct differences in the chemical environment for the two methods of Cr introduction. Surface deposition of Cr results in the formation of shoulders on the lower binding energy side for the Bi 5d peaks and two distinct Cr 3p peaks indicative of two Cr sites. These striking differences suggests an interesting possibility that better control of doping at only near surface region may offer a path to quantum anomalous Hall states at higher temperatures than reported in the literature.
Authors:
 [1] ;  [1] ;  [1] ;  [2] ;  [1] ;  [3] ;  [1]
  1. Univ. of Connecticut, Storrs, CT (United States)
  2. Princeton Univ., NJ (United States)
  3. Brookhaven National Lab. (BNL), Upton, NY (United States)
Publication Date:
Report Number(s):
BNL-114706-2017-JA
Journal ID: ISSN 0169-4332; R&D Project: PM015; KC0207010
Grant/Contract Number:
SC0012704
Type:
Accepted Manuscript
Journal Name:
Applied Surface Science
Additional Journal Information:
Journal Volume: 407; Journal Issue: C; Journal ID: ISSN 0169-4332
Publisher:
Elsevier
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY
OSTI Identifier:
1412746
Alternate Identifier(s):
OSTI ID: 1419525

Yilmaz, Turgut, Hines, William, Sun, Fu-Chang, Pletikosić, Ivo, Budnick, Joseph, Valla, Tonica, and Sinkovic, Boris. Distinct effects of Cr bulk doping and surface deposition on the chemical environment and electronic structure of the topological insulator Bi 2 Se 3. United States: N. p., Web. doi:10.1016/j.apsusc.2017.02.160.
Yilmaz, Turgut, Hines, William, Sun, Fu-Chang, Pletikosić, Ivo, Budnick, Joseph, Valla, Tonica, & Sinkovic, Boris. Distinct effects of Cr bulk doping and surface deposition on the chemical environment and electronic structure of the topological insulator Bi 2 Se 3. United States. doi:10.1016/j.apsusc.2017.02.160.
Yilmaz, Turgut, Hines, William, Sun, Fu-Chang, Pletikosić, Ivo, Budnick, Joseph, Valla, Tonica, and Sinkovic, Boris. 2017. "Distinct effects of Cr bulk doping and surface deposition on the chemical environment and electronic structure of the topological insulator Bi 2 Se 3". United States. doi:10.1016/j.apsusc.2017.02.160. https://www.osti.gov/servlets/purl/1412746.
@article{osti_1412746,
title = {Distinct effects of Cr bulk doping and surface deposition on the chemical environment and electronic structure of the topological insulator Bi 2 Se 3},
author = {Yilmaz, Turgut and Hines, William and Sun, Fu-Chang and Pletikosić, Ivo and Budnick, Joseph and Valla, Tonica and Sinkovic, Boris},
abstractNote = {In this report, it is shown that Cr doped into the bulk and Cr deposited on the surface of Bi2Se3 films produced by molecular beam epitaxy (MBE) have strikingly different effects on both the electronic structure and chemical environment. Angle resolved photoemission spectroscopy (ARPES) shows that Cr doped into the bulk opens a surface state energy gap which can be seen at room temperature; much higher than the measured ferromagnetic transition temperature of ≈ 10 K. On the other hand, similar ARPES measurements show that the surface states remain gapless down to 15 K for films with Cr surface deposition. In addition, core-level photoemission spectroscopy of the Bi 5d, Se 3d, and Cr 3p core levels show distinct differences in the chemical environment for the two methods of Cr introduction. Surface deposition of Cr results in the formation of shoulders on the lower binding energy side for the Bi 5d peaks and two distinct Cr 3p peaks indicative of two Cr sites. These striking differences suggests an interesting possibility that better control of doping at only near surface region may offer a path to quantum anomalous Hall states at higher temperatures than reported in the literature.},
doi = {10.1016/j.apsusc.2017.02.160},
journal = {Applied Surface Science},
number = C,
volume = 407,
place = {United States},
year = {2017},
month = {2}
}