Dichotomy between the hole and electrons behaviour in the multiband FeSe

Understanding the complex electronic behaviour of multiband superconductors relies on separating the contribution of different components that contribute to its conductivity. By measuring these components of the magnetoresitivity tensor both at very low temperatures using ultra-high magnetic fields up to 90 T and at high temperatures using fields up to 14 T we were able to disentangle to origin of different electronic bands. We found out that the eletronic strucuture of FeSe is composed of three different bands, having a highly mobile and small electron band, in addition to the almost compensated hole and electron bands. These findings were published in Phys. Rev. Lett. 115, 027006 (2015) and the high fields measurements were performed in Oxford and at the European Magnetic Field Laboratory at LMNCI in Toulouse in collaboration with scientists in Kyoto, Tokyo in Japan and Karlsrue in Germany.