9) Shubnikov - de Haas and de Haas - van Alphen Effects in the Vortex State of the Organic Superconductor -(BEDT-TTF)2Cu(NCS)2

@@Shubnikov - de Haas (SdH) oscillations are observed in the superconducting state of the quasi two dimensional organic superconductor -(BEDT-TTF)2Cu(NCS)2. The SdH oscillations can be observed on the broad resistive transition curve down to about 5 T at 0.5 K, where the resistivity becomes about 30 % of the normal state value. The additional damping of the SdH oscillation amplitude in the superconducting state in comparison with the normal state damping described by the Lifshitz - Kosevich formula is found below about 7 T as well as that of the de Haas - van Alphen oscillations. A novel strong damping effect is found in only the SdH effect in the quantum vortex slush region strongly affected by quantum fluctuations.

IMR, Tohoku University : Takahiko Sasaki, Toru Fukuda, Naoki Yoneyama, Norio Kobayashi

Reference : T. Sasaki, T. Fukuda, N. Yoneyama, N. Kobayashi,
"Shubnikov-de Haas effect in the quantum vortex liquid state of the organic superconductor