METAL-INSULATOR TRANSITIONS IN DOPED La-BASED SUPER CONDUCTORS WITH SMALL-RADIUS DOPANTS

n this work, we study the possibility of realizing two distinct mechanisms metal-insulator transitions in hole-doped cuprates induced by localization charge carriers near small-radius impurities and a deformable lattice (i.e. absence impurities). The purpose research is to determine criteria conditions) for existence localized states hole solve problem La-based cuprates. advantage cuprate versus other types that driven strong carrier-impurity-phonon carrier-phonon interactions occur simultaneously wider doping range from lightly doped heavily regime. We show at very low doping, separate levels are formed charge-transfer gap As level increases towards underdoped region, energy such start form bands which gradually broaden with increasing doping. propose new two-carrier superconductor model studying occurring simultaneouslyin compounds. demonstrate when reside impurity polaron bands, these superconductors dopants accordingly wide relatively lower levels.