Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Study of the electron-phonon interaction in metal diborides MeB_2
  (Me=Zr, Nb, Ta, Mg) by point-contact spectroscopy   We review investigations of the electron-phonon interaction (EPI) in metal
diborides MeB_2 (Me=Zr, Nb, Ta, Mg) by point-contact (PC) spectroscopy. For
transition metal compounds the PC EPI functions were recovered and EPI
parameter $\lambda\lesssim 0.1$ were estimated. The data are consistent with
the measured surface phonon dispersion curves. The low $\lambda$ value
questions some reports about superconductivity in these compounds. Contrary,
EPI in superconducting MgB_2 films manifests also in the PC spectra itself by
virtue of an elastic EPI contribution to the excess current determined by the
energy dependence of the superconducting order parameter. To analyse the phonon
features in the PC spectra of MgB$_2$ a two-band model is exploited and the
proximity effect in the {\bf k}-space is suggested.

23
The categories of this paper are: solv-int
29
The categories of this paper are: funct-an
13
The categories of this paper are: quant-ph
11
The categories of this paper are: hep-lat
3
The categories of this paper are: physics
10
The categories of this paper are: q-bio
30
The categories of this paper are: q-alg
18
The categories of this paper are: econ
33
The categories of this paper are: plasm-ph
35
The categories of this paper are: mtrl-th
20
The categories of this paper are: acc-phys
31
The categories of this paper are: ao-sci
16
The categories of this paper are: stat
22
The categories of this paper are: chao-dyn
26
The categories of this paper are: bayes-an
37
The categories of this paper are: supr-con