A novel method for superconducting energy gap measurement

A novel method has been developed for the measurement of the superconducting energy gap in high-temperature superconductors. The energy gap was measured by detecting the quasi-particle current through an SNS' junction, where S and S' are a high-temperature and a conventional superconductor, respectively. The advantage of this method over conventional tunneling spectroscopy lies in its applicability to superconductors with a degraded surface. A clear gaplike structure with a gap energy of 16 mV was observed for YBCO.