Resonant transport through midgap states in voltage-biased Josephson junctions of d-wave superconductors
✍ Scribed by Tomas Löfwander; Göran Johansson; Vitaly Shumeiko; Göran Wendin; Magnus Hurd
- Publisher
- Elsevier Science
- Year
- 1999
- Tongue
- English
- Weight
- 167 KB
- Volume
- 25
- Category
- Article
- ISSN
- 0749-6036
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✦ Synopsis
We study theoretically the ac Josephson effect in voltage-biased planar junctions of d-wave superconductors. For some orientations of the superconductors a current peak is found at finite voltage in the current-voltage characteristics. We pick out the relevant physical processes and write down an analytical formula for the current which clearly shows how the midgap state acts as a resonance and produces the peak. We present a possible explanation for the zero-bias conductance peak, recently found in experiments on grain boundary junctions of high-temperature superconductors, in terms of resonant transmission through midgap state of quasiparticles undergoing multiple Andreev reflections. We note that within our framework the zero-bias conductance peak appears in rather transparent Josephson junctions of d-wave superconductors.