Superconductor -Insulator Transition in Cuprates

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We present here selected achievements in this study annually. To people who want to learn the details of this work, we hope them to look at the references below.The first year:1) We found that the superconductivity in THT phase induced under pressure disappears discontinuously at x_c=0.05.2) From the tunnel spectroscopy, we found that low doped LSCO with x=0.02 which has no superconductivity has an energy gap.3) We succeeded in growing high quality single-crystals of electron doped NCCO. Ultrasonics clarified the CEF state of Nd ions.The second year:1) Detailed research on in-plane transport properties revealed that the 2-D metallic conduction is indispensable for high-Tc SC.2) We found pressure induced antiferromagnetic Mott insulator -itinerant ferromagnetic metal transition in Ca_2RuO_4.3) We detected an evidence for time irreversible 2-D SC order parameter in the T-dependence of transverse elastic modulus.The last year:1) Ultra low amplitude AC field susceptibility measurements clarified the presence of phase incoherent Cooper pair above Tc.2) We found the pressure-induced superconductor-insulator transition in a spinet compound CuRh_2S_4 for the first time.3) We firstly detected the experimental evidence for the ferroquadrupolar ordering in UCu_2Sn