A study on magnetic excitation and phase separation in the vicinity of the quantum critical point(QCP) in the strongly correlated electron system(SCES)

本项目的目的是利用微观实验技术研究铜、钴酸盐和钌酸盐化合物以及重费米子化合物（包括Ce、Yb和U离子）中qcp周围的磁波动。这里，QCP是通过改变物理参数将相变温度抑制到绝对零度的物理条件。在QCP附近，非费米液体行为被观察到，它偏离了在正常金属中看到的普通行为。我们使用核磁共振（NMR）和μ子自旋共振/旋转（μSR）作为我们的微观实验技术。我们强调，当超过核磁共振实验极限的弛豫时间很短或在极低的场中无法进行核磁共振实验时，使用μSR实验。我们证明了这两种实验技术的互补性。此外，我们还利用核磁共振和μSR测量从微观角度研究了SCES中磁性与非常规超导性之间的相互作用。在研究期间，我们研究了以下主题：a) QCPb附近的磁波动；b)铜和HF化合物的磁性与超导性的关系；c)最近发现的超导体的Knight位移测量；d)水合物钴酸盐超导体。对这一期间的研究结果进行了总结，并发表在下一页。

The aim of this program is to investigate the magnetic fluctuations around QCPs in cuprate, cobaltate, and ruthenate compounds, and heavy-fermion compounds including Ce,Yb and U ions using microscopic experimental techniques. Here, the QCP is the physical condition where the phase transition temperature is suppressed to the absolute zero by varying a physical parameter. Near the QCP, non-Fermi-liquid behavior is observed, which deviates from ordinary behaviors seen in normal metals. We use nuclear magnetic resonance (NMR) and muon spin resonance/rotation (μSR) as our microscopic experimental techniques. We have emphasized the use of μSR experiments when an NMR experiment is impossible due to the short relaxation time beyond the NMR experimental limit or in extremely low fields. We showed that the two experimental techniques are quite complementary to each other. In addition, we investigated the interplay between magnetism and unconventional superconductivity in the SCES from the microscopic point of view using NMR and μSR measurements.During the research period, we investigated the following subjects,a)magnetic fluctuations near the QCPb)the relation between magnetism and superconductivity in cuprate and HF compounds.c)Knight shift measurements in recently-discovered superconductorsd)Hydrate cobaltate superconductor.The results during the period are summarized, and are published as shown in the next page.