Syntheses of New 2-Dimensional Itinerant-Electron Compounds and Search for Novel Physical Properties

本文对二维巡回电子系统进行了研究，旨在通过控制过渡金属元素的电子态来研究和建立新型的二维巡回电子系统。结果发现，在高场磁化过程中，SrCo2P2在60T附近发生了巡回电子变磁转变。通过用Ca代替Sr，发现该体系接近2D巡游铁磁性的QCP。在二维超导体系Fe(Te-Se)中，进一步利用125Te核磁共振研究了其物理性质。因此，这种超导电性的机制被发现是由于反铁磁自旋涨落。

The research on 2-dimensional itinerant-electron systems has been conducted in order to investigate and to establish novel 2-dimensional itinerant-electron systems by controlling the electronic states of transition-metal elements. As a result, we newly found the itinerant-electron metamagnetic transitions around 60 T in the high-fieldmagnetization process of SrCo2P2. By substituting Ca for Sr, the system was found to approach the QCP of the 2D itinerant ferromagnetism. In the 2-dimensional superconductingsystem Fe(Te-Se), furthermore, physical properties were investigated by utilizing 125Te NMR. Consequently, the mechanism of this superconductivity was found to be due to the antiferromagnetic spin-fluctuation.