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Title: Selective mass enhancement close to the quantum critical point in BaFe 2(As 1-xP x) 2

A quantum critical point (QCP) is currently being conjectured for the BaFe 2(As 1-xP x) 2 system at the critical value x c ≈ 0.3. In the proximity of a QCP, all thermodynamic and transport properties are expected to scale with a single characteristic energy, given by the quantum fluctuations. Such a universal behavior has not, however, been found in the superconducting upper critical field H c2. Here we report H c2 data for epitaxial thin films extracted from the electrical resistance measured in very high magnetic fields up to 67 Tesla. Using a multi-band analysis we find that H c2 is sensitive to the QCP, implying a significant charge carrier effective mass enhancement at the doping-induced QCP that is essentially band-dependent. Our results point to two qualitatively different groups of electrons in BaFe 2(As 1-xP x) 2. The first one (possibly associated to hot spots or whole Fermi sheets) has a strong mass enhancement at the QCP, and the second one is insensitive to the QCP. The observed duality could also be present in many other quantum critical systems.
Authors:
 [1] ; ORCiD logo [2] ;  [1] ;  [2] ;  [2] ;  [3] ;  [4] ;  [5] ;  [6] ;  [7] ;  [7] ;  [8] ;  [8] ;  [9] ;  [10] ;  [10] ;  [10] ;  [10] ;  [2]
  1. Dresden Univ. of Technology (Germany); Leibniz Inst. for Solid State and Materials Research (IFW), Dresden (Germany)
  2. Leibniz Inst. for Solid State and Materials Research (IFW), Dresden (Germany)
  3. Lomonosov Moscow State Univ. (Russian Federation)
  4. Leibniz Inst. for Solid State and Materials Research (IFW), Dresden (Germany); Lomonosov Moscow State Univ. (Russian Federation)
  5. Leibniz Inst. for Solid State and Materials Research (IFW), Dresden (Germany); Karlsruhe Inst. of Technology (KIT) (Germany)
  6. Helmholtz-Zentrum Dresden-Rossendorf, Dresden (Germany)
  7. Florida State Univ., Tallahassee, FL (United States)
  8. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  9. Tokyo Univ. of Agriculture and Technology (Japan)
  10. Nagoya Univ. (Japan)
Publication Date:
Report Number(s):
LA-UR-17-23671
Journal ID: ISSN 2045-2322
Grant/Contract Number:
AC52-06NA25396
Type:
Accepted Manuscript
Journal Name:
Scientific Reports
Additional Journal Information:
Journal Volume: 7; Journal Issue: 1; Journal ID: ISSN 2045-2322
Publisher:
Nature Publishing Group
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (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; High Magnetic Field Science; Superconductor Pnictides quantum critical point
OSTI Identifier:
1396128