skip to main content

SciTech ConnectSciTech Connect

Title: Observation of cyclotron resonance and electron-phonon coupling in surface states of the bulk-insulating topological insulator Cu0.02Bi2Se3

We have utilized magneto-optical time-domain spectroscopy to investigate the low frequency optical response of topological insulator Cu0.02Bi2Se3 and Bi2Se3 films. With both field and frequency depedence, such experiments give sufficient information to measure the mobility and carrier density of multiple conduction channels simultaneously. We observe sharp cyclotron resonances (CRs) in both samples. The small amount of Cu substitution into the Cu0.02Bi2Se3 induces a true bulk insulator with only a single conduction channel with total sheet carrier density 4.9 x 1012/cm2 and mobility as large as 4000 cm2/V s. This is consistent with pure topological surface state (TSSs) conduction with a chemical potential 150 meV above the Dirac point. Hence, a true topological insulator with an insulating bulk is realized. The CR broadens at high fields, an e ect that we attribute to an electron-phonon interaction. This assignment is supported by an extended Drude model analysis on the zero field data. In contrast to Cu0.02Bi2Se3, two charge channels were observed in normal Bi2Se3 films. We demonstrate a method to distinguish between the dominant TSSs and trivial bulk/2DEG states. The dominant channel exhibits a CR with a carrier density of ~2.0 x 1013/cm2 and mobility ~3200 cm2/V s, consistent with TSSs withmore » a chemical potential ~350meV above the Dirac point.« less
Authors:
 [1] ;  [2] ;  [1] ;  [3] ;  [3] ;  [3] ;  [1]
  1. Johns Hopkins Univ., Baltimore, MD (United States). The Inst. of Quantum Matter
  2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  3. Rutgers Univ., Piscataway, NJ (United States). Dept. of Physics and Astronomy
Publication Date:
OSTI Identifier:
1169666
Report Number(s):
LA-UR--15-20835
DOE Contract Number:
AC52-06NA25396
Resource Type:
Technical Report
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 36 MATERIALS SCIENCE Material Science