We observed superconductivity-induced conductance oscillations, arising from quasiparticle interference effects in a single normal-metallic (N) electrode of finite width in contact with a superconductor (S). A 10 × 10 μm2 Al patch was overlaid on a pre-evaporated 0.5-μm-wide mesoscopic silver wire. A phase gradient along the N/S interface was induced by applying a magnetic field perpendicular to the plane of the superconducting Al patch. The conductance across the N/S interface showed Fraunhofer-like oscillations with amplitudes of a small fraction of 2e2/h per conducting channel, for fields up to 450 G. For sufficiently low fields and temperatures the interfacial diffraction effect of quasiparticles is more complicated due to the field-induced electron-hole dephasing effect. None the less, the overall feature of the oscillatory magnetoconductance from the N/S interface appears to confirm the diffraction of Andreev-reflected quasiparticles proposed theoretically for a single N/S interface with a phase gradient.
Bibliographical noteFunding Information:
This work was supported by BSRI and MARC in POSTECH, and by the center for excellency (SRC) administered by KOSEF.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Energy Engineering and Power Technology
- Electrical and Electronic Engineering