Superconductor -Insulator Transition in Cuprates

我们每年都会在这里介绍一些研究成果。对于那些想了解这项工作细节的人，我们希望他们看看下面的参考资料。第一年：1)我们发现在压力下诱导的THT相超导性在x_c=0.05.2时不连续消失。从隧道光谱中，我们发现x=0.02的低掺杂LSCO没有超导性，存在能隙。3)成功制备了高质量的电子掺杂NCCO单晶。超声波澄清了Nd离子的CEF状态。第二年：1)对高tc SC的平面内输运性质进行了详细的研究，揭示了二维金属传导是高tc SC不可缺少的；2)在ca_2ruo_中发现了压力诱导的反铁磁Mott绝缘子-流动铁磁金属跃迁；3)在横向弹性模量的t依赖性中发现了时间不可逆的二维SC序参量的证据。去年：1)超低幅交流场磁化率测量澄清了tc .以上相非相干库珀对的存在。2)首次在自旋化合物CuRh_2S_4中发现了压力诱导的超导体-绝缘体跃迁。3)首次发现了UCu_2Sn中铁四极有序的实验证据

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