Superconductivity and ferromagnetism are very rarely found to co-exist in natural materials. However, artificially fabricated nanostructures can now be produced where a superconductor, YBa₂Cu₃O_7-x (YBCO) and colossal magneto-resistance magnetic material, La_2/3Ca_1/3MnO₃ (LCMO) are grown in alternating layers on a SrTiO₃ substrate. These structures exhibit novel quantum states that do not exist in the constituent materials, and such systems are of potential interest for spintronics applications. Off-specular neutron reflectivity measurements performed on CRISP have revealed rich in-plane magnetisation behaviour. On cooling through the cubic to tetragonal phase transition of the SrTiO₃ subphase, the Bragg peak resulting from the multilayer structure splits due to the twinning of the SrTiO₃ crystal. On cooling further, through the superconducting transition temperature of the film, the Bragg feature splits again as shown in the figure. This is indicative of the formation of a stripe domain structure with a length scale of tens of microns. This large length scale gives clues as to the mechanism driving the interaction between superconductivity and magnetism in these films, providing a tantalising glimpse into the interplay between these two effects in the multilayer structure.

J Chakhalian, J Strempfer, G Khaliullin, C Bernhard, G Cristiani, H-U Habermeier, B Keimer (Max Planck Institute, Germany), T Charlton and R Dalgliesh (ISIS), JW Freeland and G Srajer (Argonne National Lab, USA), J Cezar (ESRF, France)

Research date: December 2006

Further Information

J Chakhalian et al., Nature Physics 2 (2006) 244.​