Point-contact spectroscopy of MgB2

Point-contact Spectroscopy of Superconductors

Point-contact investigations of challenging superconductors: two-band MgB2, antiferromagnetic HoNi2B2C, heavy fermion UPd2Al3, paramagnetic MgCNi3

An overview on recent efforts in point-contact (PC) spectroscopy of title superconductors is given. Distinct phonon features and crystalline-electric-field effects are observed in PC spectra of HoNi2B2C. Results of study of superconducting (SC) gap and excess current versus temperature and magnetic field reflecting specific multi-band electronic structure in MgB2 are presented. The nature of th...

Scanning tunnelling microscopy and spectroscopy of MgB2

Experiments of the scanning tunnelling microscopy and spectroscopy (STM/STS) have been carried out on the layered superconductor MgB2 with Tc = 39 K. The measurements were done at 5 K using a Pt-Ir tip and the single-crystal grain. The STM images show characteristic hexagonal patterns with the distances of nearest neighbour atoms to be 0.3 – 0.35 nm and 0.15 – 0.2 nm, respectively, which are co...

Point-contact Spectroscopy of Magnesium Diboride with Different Counter-electrodes

We report on tunneling and Andreev-reflection conductance spectra of 39 K superconducting magnesium diboride, obtained with Pb and Au counter-electrodes. Two distinct steps at close to 2.7 and 7.1 meV appear in a low-resistance metallic-type Au-MgB2 junction characteristic, whereas a tunneling-like spectrum measured for the same junction, annealed by the application of dc current, exhibits only...

Point-contact Spectroscopy of the Nickel Borocarbide Superconductors

An overview of the recent efforts in point-contact (PC) spectroscopy of the nickel borocarbide superconductors RNi2B2C in the normal and superconducting (SC) state is given. The results of measurements of the PC electronboson(phonon) interaction spectral function are presented. Phonon maxima and crystalline-electric-field (CEF) excitations are observed in the PC spectra of compounds with R=Dy, ...