| Summary: | 碩士 === 國立臺灣師範大學 === 物理學系 === 97 === Superconductivity is an important research subject in condensed-matter physics. In last 20s years, the copper-based high-temperature superconductors (HTSC), called the cuprates, have been discovered and many subsequent studies have been done. However, there remains some unsolved subtlety, such as the superconducting mechanism and the pairing symmetry. In January of last year, the iron-based HTSC were discovered, and many scientists believed that these new type of HTSC might hold the key to solve problems of HTSC as mentioned previously. In this thesis, we present a theoretical study of pairing symmetry of iron-based HTSC (e.g. LaFxO1-xFeAs) by the Green’s function method. There are several candidates of the pairing symmetry proposed, to which we calculated the spin response for three types of gap function (i.e. s±, extended-s, and dx2 - y2 wave). It is found that the s± wave is most favored in either electron or hole doping and it agrees well with recent inelastic neutron scattering experiments. Moreover, we have also studied the effect of Hund’s coupling through the random-phase approximation vertex correction
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