Отличительные особенности фазовых диаграмм тонких неупорядоченных пленок на основе ВТСП YBa-=SUB=-2-=/SUB=-Cu-=SUB=-3-=/SUB=-O-=SUB=-7-x-=/SUB=- во внешних магнитных полях

An unusual decrease in the slope of the upper critical field near T _ c 0 at a gradual increase in the ion implantation dose has been experimentally observed in narrow bridges formed on the base of thin HTSC YBa_2Cu_3O_7 – _ x films, while an increase in the defect concentration usually leads to an increase in the local slope of the phase transition line H _ c 2( T ). In addition, it has been found that the temperature dependence of the upper critical field has a positive curvature near T _ c 0. A possible theoretical interpretation of the results is proposed. It is based on the modified Ginzburg–Landau theory with a nonuniform length of superconducting correlations.