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Title: Reexamination of the effective fine structure constant of graphene as measured in graphite

Here we present a refined and improved study of the influence of screening on the effective fine structure constant of graphene, α*, as measured in graphite using inelastic x-ray scattering. This followup to our previous study [J. P. Reed et al., Science 330, 805 (2010)] was carried out with two times better energy resolution, five times better momentum resolution, and an improved experimental setup with lower background. We compare our results to random-phase approximation (RPA) calculations and evaluate the relative importance of interlayer hopping, excitonic corrections, and screening from high energy excitations involving the sigma bands. We find that the static, limiting value of α* falls in the range 0.25-0.35, which is higher than our previous result of 0.14, but still below the value expected from RPA. We show the reduced value is not a consequence of interlayer hopping effects, which were ignored in our previous analysis, but of a combination of excitonic effects in the π→ π* particle-hole continuum, and background screening from the σ-bonded electrons. We find that σ-band screening is extremely strong at distances of less than a few nanometers, and should be highly effective at screening out short-distance, Hubbard-like interactions in graphene as well as othermore » carbon allotropes.« less
Authors:
 [1] ;  [1] ;  [1] ;  [2] ;  [3] ;  [3] ;  [1] ;  [4]
  1. Univ. of Illinois, Urbana, IL (United States). Federick Seitz Materials Research Lab., Dept. of Physics
  2. Univ. of Oklahoma, Norman, OK (United States). Dept. of Physics and Astronomy
  3. Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
  4. Univ. of Illinois, Urbana, IL (United States). Federick Seitz Materials Research Lab., Dept. of Physics; Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Publication Date:
Grant/Contract Number:
AC02-06CH11357; FG02-06ER46285; DMR-1352604; GBMF4542
Type:
Accepted Manuscript
Journal Name:
Physical Review, B: Condensed Matter
Additional Journal Information:
Journal Volume: 93; Journal Issue: 19; Journal ID: ISSN 0163-1829
Publisher:
American Physical Society (APS)
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); National Science Foundation (NSF)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; IXS; graphene
OSTI Identifier:
1362106
Alternate Identifier(s):
OSTI ID: 1254343