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 the extremely nonlinear I(V) curves in the antiferromagnetic (AF) and SC state are elucidated for UPd2Al3 break-junctions and MgCNi3 point contacts. 
Yu. G. Naidyuk, O. E. Kvitnitskaya, I. K. Yanson, G. Fuchs, K. Nenkov,   S.-L. Drechsler, G. Behr, D. Souptel, and K. Gloos