Magneto-optical setup for in situ strain and transport measurements on superconductors

A recently developed magneto-optical (MO) imaging setup for investigations on superconductors is reported. The main originality of our setup is its ability to combine both strain and transport measurements in the temperature range of 6-300 K with magneto-optical observations. We give here some theoretical considerations on the cryostat conception, which is a key point of our setup. In particular, the thermal and mechanical aspects are discussed. A detailed description of the MO setup and of the associated strain apparatus is given. Additionally, an example of MO strain and transport study on DyBCO coated conductors is given. Evidence of Luders Bands formation under strain in the Hastelloy is revealed by the field penetration inside cracks in the DyBCO and MgO layers. A correlation between the damaging morphology and the critical current at 70 K versus strain has been established.