Fabrication and characterisation of underdoped YBa2Cu3O7-delta thin films

Thin c-axis films of YBa2Cu3O7-delta have been grown on single crystal (001 ) MgO by pulsed laser deposition. The films have been deoxygenated by sinte ring and annealing in a reduced pressure of O-2. The process is reproducibl e, controllable and reversible. The reduction in T-c is accompanied by a sy stematic elongation in c-axis, facilitating an inference of delta. Resistan ce measurements show a departure from linearity at the pseudogap formation temperature T*, which has been determined as re function of delta.