Critical Fields and Anisotropy of NdO0.82F0.18FeAs Single Crystals

摘要: The newly discovered iron-based superconductors have stimulated enormous interests in the field of superconductivity. Since new superconductor is a layered system, anisotropy parameter with first priority to know. Meanwhile any relevant message about critical fields (upper and irreversibility line) are essentially important. By using flux method, we successfully grown single crystals NdO0.82F0.18FeAs at ambient pressure. Resistive measurements reveal surprising discovery that \Gamma = (mc/mab)^{1/2} below 5, which much smaller than theoretically calculated results. data measured up 400 K show continuing curved feature prevents conjectured linear behavior for an unconventional metal. upper determined based on Werthamer-Helfand-Hohenberg formula H_{c2}^{H||ab}(T=0 K) 304 T H_{c2}^{H||c}(T=0 K)=62-70 T, indicating very encouraging application superconductors.