Сверхпроводимость, инициированная электрическим полем в высокотемпературном сверхпроводнике при T>T-=SUB=-c-=/SUB=-

The theory of occurrence of superconductivity in the plate of high-temperature superconductor under electric field vertical to it, when the carrier concentration lies outside of the region of existence of superconductivity at the temperature T < $$T_{{\text{c}}}^{{\max }}$$ , was developed. The calculation was carried out for the layer of lanthanum strontium cuprate under the fields of 10^–1 V/nm ≥ E ≥ 10^–2 V/nm at various temperatures and hole concentrations. It was demonstrated that the quasi-two-dimensional superconducting layer of several Angstrom in thickness occurs near surface of the plate, moreover thickness of this layer does not depend on magnitude of the field, and depends only on temperature and on hole concentration.

EVIDENCE OF CHARGED POLARON ARRAYS FROM THE OPTICAL CONDUCTIVITY OF LANTHANUM-STRONTIUM CUPRATE

The optical conductivity of a series of LSCO single crystals with 0 < x < 0.15 is measured as a function of doping and temperature from 20000 down to 15 cm -1. The behaviour of the polaron conductivity is isolated and analyzed through its first frequency moment. A softening of the polaron binding energy EP with cooling and doping is observed, and an explanation is proposed in terms of polaron stripe formation.