NQR Study of Superconducting Mechanism mediated by Valence Fluctuations

我们研究了高压下强关联电子系统中的奇异超导机制，并试图解释导致电子间强库仑相互作用的新的对相互作用（原子价和/或轨道涨落）。在CeCu_2Si_2中，Cu核的NQR频率（^<63>ν_Q）<63>偏离了压力的线性关系。所观察到的^ ν_Q的向下偏移<63>与Ce价态的增加有关。四岁以上。5GPa时，<63>再次观察到^ ν_Q的线性关系，这与向高价态的急剧跃迁密切相关。

We study mechanism of exotic superconductivity in strongly correlated electron system under high pressure, and challenge to elucidate novel pairing interactions(valence and/or orbital fluctuations), resulting in strong coulomb interaction between the electrons. NQR frequency(^<63>ν_Q) for^<63> Cu nuclei in CeCu_2Si_2 deviates from the linear pressure dependence. The observed downward deviation of^<63>ν_Q is associated with increase of Ce valence. Above 4. 5 GPa, the linear relation of^<63>ν_Q is observed again, closely related to sharp crossover to high valence state.