Abstract
We have used the pulsed laser deposition (PLD) technique followed by post-annealing process with magnesium vapor at 700(a similar to)C for 30 min to grow a high-quality CrO2/MgB2 bilayer prepared on Al2O3 (1102) single crystal. The X-ray diffraction patterns showed high-quality orientated growth of MgB2 phase. The obtained films were approximately 300 nm thick and had lateral dimensions of 5x5 mm(2). SQUID magnetometry, magneto-optical Faraday microscopy, and magneto-transport techniques were used in order to measure the critical current density (J(C)) that was found to be 7- 9x10(6) A/cm(2) at 15 K. Transition temperature (T-C) for the films was similar to 37 K. The obtained magnetic hysteresis loops at low temperatures exhibited asymmetry with respect to H = 0. This can be explained in terms of pinning of flux lines in the films due to magnetic interaction with the ferromagnetic CrO2 layer.