Strong evidence of field-induced superconductivity and Shubnikov-de Haas oscillation in $\kappa $-(BETS)$_{2}$FeBr$_{4}$

High field electronic state of the quasi-two dimensional organic superconductor, $\kappa $-(BETS)$_{2}$FeBr$_{4 }$was investigated. Under the magnetic field exactly parallel to the conducting layers, zero resistance was observed in the region of about $11 \sim 14$ T at 27 mK. This is the strong evidence of the field induced superconductivity in this salt. In the antiferromagnetic state below 5 T, Shubnikov-de Haas oscillation with a low frequency of 62 T was observed. This new frequency can be ascribed to a small pocket formed by the reconstruction of the Fermi surface due to the antiferromagnetic order. Key words. Organic conductors – Field induced superconductivity – Shubnikov-de Haas oscillatio