Electron-phonon interaction in transition metal diborides TB_2 (T=Zr,   Nb, Ta) studied by point-contact spectroscopy
  The electron-phonon interaction (EPI) in transition metal diborides TB_2 (T=Zr, Nb, Ta) is investigated by point-contact (PC) spectroscopy. The PC EPI functions were recovered and the EPI parameters lambda<0.1 were estimated for all three compounds. Common and distinctive features between the EPI functions for those diborides are discussed also in connection with the superconductivity in MgB_2. 
Yu.G. Naidyuk, O.E. Kvitnitskaya, I.K. Yanson, S.-L. Drechsler, G.   Behr, and S. Otani