New approach to the high temperature superconductor based on Fe oxychalcogenides

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Motivated by recent finding of high temperature superconductivity and controversial issues on its mechanism in metallic Fe-pnictides and Fe-chalcogenides, we’ve proposed 1)the new approach to synthesize a superconductor from insulating oxychalcogenide which shares a structural property but has different origin of magnetism, and 2) to study magnetism in the view point of localized electron which will give more clear insight on understanding obscure mechanism of superconductivity not only in Fe-based superconductors but also in high Tc cuprate. We succeeded to synthesize high quality powder samples of non-doped oxychalcogenides (La2O2Fe2Se2, La2O2Fe2OS2, LaOCo2OSe2 and La2OMn2OSe2), which are base materials for the next step to synthesize superconductors by doping carriers. In order to characterize macroscopic and microscopic properties of non-doped compounds, elastic and inelastic neutron scattering measurements methods have been utilized to explore static and dynamic properties of magn … More etic ground states. In the case of Fe-oxychalcogenide (La2O2Fe2Se2 and La2O2Fe2OS2), it turns out to be highly frustrated magnets in the checkerboard type lattice showing unusual magnetic spin fluctuation even at room temperature far beyond magnetic ordering temperature. While there exist no serious frustrating effect in Co- and Mn-oxychalcogenides, an extraordinary magnetic excitation and fluctuation have been observed regarding on the unquenched orbital magnetic moment in the Co sample and extremely low dimensional magnetic 機関番号：82121 研究種目：若手研究(B) 研究期間：2011～2012 課題番号：23740254 研究課題名（和文）高温超伝導体への新規アプローチ:Fe酸化物絶縁体を用いて 研究課題名（英文）New approach to the high temperature superconductor based on Fe oxychalcogenides 研究代表者 池 聖大(SUNGDAE JI） 一般財団法人総合科学研究機構（総合科学研究センター（総合科学研究室）及び東海事業・その他部局等・研究員 研究者番号：10594898 interaction in the Mn sample, respectively. Our experimental results about parent materials have shown that oxychalogenides are good toy models for studying novel magnetism with various spin/orbital states such as geometrical frustration in the checkerboard lattice, orbital excitation from extraordinary unquenched moments and low dimensionality in Ising type ground states. Less