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Title: Experimental observation of incoherent-coherent crossover and orbital-dependent band renormalization in iron chalcogenide superconductors

The level of electronic correlation has been one of the key questions in understanding the nature of superconductivity. Among the iron-based superconductors, the iron chalcogenide family exhibits the strongest electron correlations. To gauge the correlation strength, we performed a systematic angle-resolved photoemission spectroscopy study on the iron chalcogenide series Fe1+ySexTe1-x (0 < x < 0.59), a model system with the simplest structure. Our measurement reveals an incoherent-to-coherent crossover in the electronic structure as the selenium ratio increases and the system evolves from a weakly localized to a more itinerant state. Furthermore, we found that the effective mass of bands dominated by the dxy orbital character significantly decreases with increasing selenium ratio, as compared to the dxz/dyz orbital-dominated bands. The orbital-dependent change in the correlation level agrees with theoretical calculations on the band structure renormalization, and may help to understand the onset of superconductivity in Fe1+ySexTe1-x.
Authors:
 [1] ;  [1] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6] ;  [7] ;  [8] ;  [9] ;  [10] ;  [10] ;  [11] ;  [3] ;  [8] ;  [1]
  1. SLAC National Accelerator Lab., Menlo Park, CA (United States); Stanford Univ., CA (United States)
  2. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS); SLAC National Accelerator Lab., Menlo Park, CA (United States)
  3. Tulane Univ., New Orleans, LA (United States)
  4. Renmin Univ. of China, Beijing (China); Rice Univ., Houston, TX (United States)
  5. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  6. Boston College, Chestnut Hill, MA (United States)
  7. Univ. of Oxford (United Kingdom)
  8. SLAC National Accelerator Lab., Menlo Park, CA (United States). Stanford Synchrotron Radiation Lightsource (SSRL)
  9. SLAC National Accelerator Lab., Menlo Park, CA (United States)
  10. Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Advanced Light Source (ALS)
  11. Rice Univ., Houston, TX (United States)
Publication Date:
OSTI Identifier:
1393003
Grant/Contract Number:
AC02-05CH11231; AC02-76SF00515
Type:
Accepted Manuscript
Journal Name:
Physical Review. B, Condensed Matter and Materials Physics
Additional Journal Information:
Journal Volume: 92; Journal Issue: 23; Journal ID: ISSN 1098-0121
Publisher:
American Physical Society (APS)
Research Org:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (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