In 1975, he synthesized the first superconducting compounds containing a regular lattice of magnetic ions, a discovery opening up a decade of international research concerning the interaction between magnetism and superconductivity. This work was highlighted by his discovery in 1984 of superconductivity induced via magnetic field. With his team, Fischer launched the first artificial superlattices of superconductor cuprates, the pioneering work of many developments in new areas of thin films and oxide interfaces. From 1986, Fischer assigned a part of his team to work in scanning tunneling microscopy which allowed him to probe the fundamental properties of high temperature superconductors. In 2001, he founded and became director of the NCCR (PRN) MaNEP dedicated to the study of materials with novel electronic properties.