DIMENSIONAL CROSSOVER AND LOCALIZATION OF SUPERCONDUCTING LAYERS IN SEMICONDUCTING MULTILAYERS PBTE PBS/

Resistive transitions in magnetic fields have been investigated on the superconducting PbTe/PbS multilayers with different superstructure pe riods, From these transitions parallel and perpendicular critical magn etic fields have been determined. In parallel fields the temperature d ependence of the critical field sharply changes, suggesting the dimens ional 3D-2D crossover. In samples of limited (total) thickneses with a relatively small number of bilayers, double crossover has been found. For all samples the superstructure period determined from the superco nducting characteristics is equal to half the period determined from x -ray diffraction patterns. This fact indicates that superconductivity in these semiconducting multilayers is associated with the interface b etween two semiconducting layers containing networks of mismatch dislo cations. This conclusion is confirmed also by the data on double cross over. The thickness of superconducting layers estimated from experimen tal data correlates with D for all samples. It is shown that significa nt broadening of the resistive transitions similar to that observed on single crystals of high-T(C) superconductors does not prevent proper determination of the multilayer parameters.