1 research outputs found
In situ annealing of superconducting MgB2 films prepared by pulsed laser deposition
The in situ annealing conditions of pulsed laser deposited MgB2 films were
studied. The precursor films were deposited at 250 C from a stoichiometric MgB2
target in a 120mTorr Ar atmosphere. The films were then in situ annealed at a
temperature from 450 C to 800 C and an annealing time from 1 minute to 10
minutes. We found that the superconducting properties depend in a crucial way
on the annealing conditions: temperature, heating rate and time. The best film
with a thickness of ~600nm was obtained under the following annealing
conditions: Tanneal=680-690 C, tanneal=1 min, heating rate= 38 C/min. The Tc
onset of the film is 28K with a transition width of ~10K. The hysteresis loop
of magnetic moment of the film indicates weak field dependence in high fields.
Magneto-optical imaging of the film showed quite homogeneous magnetic flux
penetration, indicating structural homogeneity. The films without annealing
showed no superconductivity.Comment: 12 pages, 6 figure