Observation of the Andreev reflection in the c-axis transport of Bi2Sr2CaCu2O8+x single crystals near T-c and the search for the preformed-pair state
SCIE
SCOPUS
- Title
- Observation of the Andreev reflection in the c-axis transport of Bi2Sr2CaCu2O8+x single crystals near T-c and the search for the preformed-pair state
- Authors
- Chang, HS; Lee, HJ; Oda, M
- Date Issued
- 2001-10-01
- Publisher
- AMERICAN PHYSICAL SOC
- Abstract
- We observed an enhancement of the c-axis differential conductance around the zero bias. in Au/Bi2Sr2CaCu2O8+x (Bi2212) junctions near the superconducting transition temperature T-c. We attribute the conductance enhancement to the Andreev reflection between the surface Cu-O bilayer with suppressed superconductivity and the neighboring superconducting inner bilayer. The continuous evolution from depression to an enhancement of the zero-bias differential conductance, as the temperature approaches T-c from below, points to weakening of the barrier strength of the nonsuperconducting layer between adjacent Cu-O bilayers. We observed that the conductance enhancement persisted up to a few degrees above T-c in junctions prepared on slightly overdoped Bi2212 crystals. However, no conductance enhancement was observed above T-c in under-doped crystals, although a recently proposed theoretical consideration suggests an even wider temperature range of enhanced zero-bias conductance. This seems to provide a negative perspective to the existence of the phase-incoherent preformed pairs in the pseudogap state.
- URI
- https://oasis.postech.ac.kr/handle/2014.oak/12064
- DOI
- 10.1103/PhysRevB.64.134504
- ISSN
- 0163-1829
- Article Type
- Article
- Citation
- PHYSICAL REVIEW B, vol. 64, no. 13, 2001-10-01
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