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This content will become publicly available on May 7, 2019

Title: Anomalous density fluctuations in a strange metal

A central mystery in high-temperature superconductivity is the origin of the so-called strange metal (i.e., the anomalous conductor from which superconductivity emerges at low temperature). Measuring the dynamic charge response of the copper oxides, χ"(q,ω), would directly reveal the collective properties of the strange metal, but it has never been possible to measure this quantity with millielectronvolt resolution. Here, we present a measurement of χ"(q,ω) for a cuprate, optimally doped Bi 2.1Sr 1.9CaCu 2O 8+x (T c = 91 K), using momentum-resolved inelastic electron scattering. In the medium energy range 0.1–2 eV relevant to the strange metal, the spectra are dominated by a featureless, temperature- and momentum-independent continuum persisting to the electronvolt energy scale. This continuum displays a simple power-law form, exhibiting q 2 behavior at low energy and q 22 behavior at high energy. Measurements of an overdoped crystal (T c = 50 K) showed the emergence of a gap-like feature at low temperature, indicating deviation from power law form outside the strange-metal regime. In conclusion, our study suggests the strange metal exhibits a new type of charge dynamics in which excitations are local to such a degree that space and time axes are decoupled.
ORCiD logo [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [1] ;  [2] ;  [3] ;  [4] ;  [4] ;  [4] ;  [1]
  1. Univ. of Illinois, Urbana-Champaign, IL (United States). Dept. of Physics; Univ. of Illinois, Urbana-Champaign, IL (United States). Materials Research Lab.
  2. Karlsruhe Inst. of Technology (KIT) (Germany). Inst. for the Theory of Condensed Matter
  3. Univ. of Oklahoma, Norman, OK (United States). Dept. of Physics and Astronomy
  4. Brookhaven National Lab. (BNL), Upton, NY (United States). Condensed Matter Physics and Materials Science Dept.
Publication Date:
Report Number(s):
Journal ID: ISSN 0027-8424
Grant/Contract Number:
SC0012704; AC02-98CH10886; GBMF4542; DMR-1352604
Accepted Manuscript
Journal Name:
Proceedings of the National Academy of Sciences of the United States of America
Additional Journal Information:
Journal Volume: 115; Journal Issue: 21; Journal ID: ISSN 0027-8424
National Academy of Sciences, Washington, DC (United States)
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
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 36 MATERIALS SCIENCE; non-Fermi liquid; strange metal; cuprates; quantum criticality; electron energy-loss spectroscopy
OSTI Identifier:
Alternate Identifier(s):
OSTI ID: 1438288