Enhancement of superconductive critical temperatures in almost empty or full bands in two dimensions: possible relevance to beta-HfNCl, C60 and MgB2
arXiv:cond-mat/0103352 · doi:10.1142/S0217984901001707
Abstract
We examine possibility of enhancement of superconductive critical temperature in two-dimensions. The weak coupling BCS theory is applied, especially when the Fermi level is near the edges of the electronic bands. The attractive interaction depends on due to screening. The density of states(DOS) does not have a peak near the bottom of the band, but -dependent contribution to DOS (electron density on the Fermi surface) has a diverging peak at the bottom or top. These features lead to significant enhancement of the critical temperatures. The results are qualitatively consistent with the superconductive behaviors of HfNCl ($\Tc \le 25K$) and ZrNCl($\Tc \le 15K$), C with a field-effect transistor configuration ($\Tc = 52K$), and MgB ($\Tc \approx 40K$) which have the unexpectedly high superconductive critical transition temperatures.
5 pages,4 figures