Crossover between Superconductivity and Magnetism in YBa2Cu3O7-SrRuO3 nanostructures
V. Suresh Kumar1,2*, J. C. Lin2, H. J. Liu2, Z.Zhang3, Y. C. Chen1, J. Y. Lin4, Y. H. Chu2,4
1Department of Physics, National Cheng Kung University, Tainan, Taiwan
2Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu, Taiwan
3Department of Materials Science and Engineering, 3Erich Schmid Institute of Materials Science, Austria
4Department of Electrophysics, National Cheng Kung University, Hsinchu, Taiwan
* presenting author:Vandrangi Suresh,
By a systematic variation of doping concentration of itinerant ferromagnetic SrRuO3 (SRO) in the matrix of superconducting YBa2Cu3O7 (YBCO), forming nanostructures that are structurally phase separate, we are able to demonstrate metal to insulator transition in the normal state of YBCO (the high temperature regime of YBCO-SRO nanostructures) and a crossover between superconductivity and magnetism at low temperatures. Starting from a much diluted concentration of SRO in YBCO-SRO nanostructures, which exhibits an insulating phase at high temperatures and superconducting phase at low temperatures, by increasing the magnetic interactions as a function of SRO doping, we investigated the electronic correlations and the interplay between superconductivity and magnetism throughout the temperature regime. For the first time, we show the Mott transition in charge-transfer type superconductor. A crossover from the superconducting phase to the magnetic phase with increasing density of nano-size SRO crystallites in the YBCO matrix is observed as a consequence of competing interactions between these two ordered phases.

Keywords: thin-film heterostructures, Superconductivity, Magnetism