Tunneling Measurement for the Energy Gap in Quaternary Compound Superconductors YNi2B2C, LuNi2B2C and YBCO by LTSTM
G. T. Jeong；J. I. Kye；S. H. Chun；W. K. Park；Z. G. Khim；W. C. Lee；P. C. Canfield；B. K. Cho；D. C. Johnston
Chinese Journal of Physics
|Volume or Term/Year and Month of Publication||
34卷2S期（1996 / 04 / 01）
406 - 413
Tunneling spectra of a single crystalline YNi2B2C (Tc = 15.4 K), LuNi2B2C (Tc= 15.7 K) and YBCO (Tc = 90 K) have been measured by a point contact spectroscopy using a low temperature scanning tunneling microscope. The conductance curve of RNi2B2C shows a smeared gap structure with an almost linear density of states inside of the gap region. The linear conductance inside the gap region has been explained by a proximity induced energy gap in the degraded surface normal layer. c-axis oriented YBCO films shows periodic current steps at the corresponding voltage of V = (2n+1)V0. Voltage period ΔV shows a dependence on the sample-to-tip distance implying the single electron tunneling nature.