The metal–insulator transition induced in Bi2Sr1.93Cu1.01O6+δ thin films by oxygen concentration in sputtering gas

Effect of Yb, Gd, and Nd Substitution at the Sr Site on the Metal–Insulator Transition of the (Bi,Pb)‐2212 System

“…2 This underdoping of charge carriers can be achieved by doping these systems with REs at the cationic sites that reduce the carrier concentration (holes) of the system by supplying electrons. There are reports that show that RE doping at the Sr site of Bi-2201 or the Ca/Sr site of Bi-2212 changes its superconducting properties and, at a higher level of doping, the superconducting properties disappear and MIT occurs in different forms such as polycrystalline, 5,[9][10][11] thin films, 6,12 and single crystals. 2 When MIT occurs, the material shows a clear upturn of resistivity from a metallic (dr/dT40) to an insulating nature (dr/dTo0) at low temperatures.…”