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Energy gaps in Bi(2)Sr(2)CaCu(2)O(8+δ) cuprate superconductors
1Beijing National Laboratory for Condensed Matter Physics, Institute of Physics , Chinese Academy of Sciences, Beijing 100190, China.
Scientific Reports
|February 23, 2012
Summary
Superconducting pairing in cuprates begins above the critical temperature (Tc) on a limited Fermi surface. This pairing then expands to the entire Fermi surface, forming a d-wave superconducting gap at lower temperatures.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Quantum Materials
Background:
- The relationship between the cuprate pseudogap (Δ(p)) and superconducting gap (Δ(s)) is a key unresolved issue in understanding high-temperature superconductivity.
- Cuprates exhibit complex electronic phases, including the pseudogap and superconductivity, with their interplay being a subject of intense research.
Purpose of the Study:
- To investigate the temperature and doping dependence of the superconducting gap (Δ(s)) in relation to the pseudogap (Δ(p)).
- To elucidate the emergence and evolution of superconducting pairing in cuprate materials.
Main Methods:
- Utilized temperature- and doping-dependent tunneling spectroscopy.
- Employed submicron Bi(2)Sr(2)CaCu(2)O(8+δ) intrinsic Josephson junctions to probe electronic properties.
Main Results:
- Demonstrated that Δ(s) closes at a temperature T(c)(0) significantly above the superconducting transition temperature (T(c)) but below the pseudogap temperature (T*).
- Observed initial superconducting pairing predominantly near the Fermi surface node, forming a 'Fermi arc'.
- Showed the Fermi arc length exhibits linear temperature dependence and vanishes as pairing extends to the antinodal region.
Conclusions:
- Superconducting pairing initiates above T(c) on a restricted part of the Fermi surface.
- The observed Fermi arc is attributed to quasiparticle and Cooper pair lifetime effects.
- As temperature decreases, pairing expands across the entire Fermi surface, resulting in a d-wave superconducting gap.
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