Vz. Kresin et al., ENERGY-SPECTRUM OF HIGH-T-C OXIDES - 2-GAP STRUCTURE, GAPLESSNESS, AND IMPLICATIONS, Journal of physics and chemistry of solids, 56(12), 1995, pp. 1623-1626
The energy spectrum of the cuprates depends on the level of doping. De
viation from stoichometry may introduce magnetic impurities, which, in
turn, lead to a gapless scenario with peculiar optical, transport, ma
gnetic and thermodynamic properties.