Heavy fermion state inpressme-indumd superconductor studied by the de Haas-van Alphen effect under pressure

铈化合物的f电子表现出多种特征，包括自旋和荷序、自旋和价涨落、重费米子和各向异性超导性。在铈化合物中，Rudemran-Kittel-Kasuya-Yosida （RKKY）相互作用和近藤效应相互竞争。RKKY相互作用增强了远端磁序，而近藤效应使局域f电子的磁矩猝灭。由于RKKY相互作用克服了低温下的近藤效应，大多数铈化合物在尼尔温度T_N下呈反铁磁序。近年来，发现了铈、铀磁性有序化合物的一个新方面。当对CeCu_2Ge_2、CeIn_3和CePd_2Si_2等具有反铁磁有序的化合物施加P压力时，在量子临界压力Pc下，T_N达到零，并在P_c附近观察到超导性。在压力下，从磁性有序态到非磁性态的跃迁，跨越量子临界点，是强相关电子系统中最有趣的问题。我们开发了用于de Haas-van Alphen实验和电阻率测量的可在磁场中旋转的高压电池，并研究了包括压力诱导超导体在内的重费米子态，总结如下：1。压力感应超导体CeIrSi_3和CeCoGe_3及其具有强耦合行为的巨大上临界场的发现2。基于非对对称晶体结构的CeTX_3 （T：过渡金属，X: Si, Ge）中反对称自旋-轨道相互作用的分裂费米表面。Ce_2Ni_3Ge_5和CePt_3Si的压力诱导重费米子超导性，4。铁磁体CePtAl和反铁磁体CeTl_3的压力相图

The f electrons of cerium compounds exhibit a variety of characteristic features including spin and charge orderings, spin and valence fluctuations, heavy-fermions and anisoiropic superconductivity. In cerium compounds, the Rudemran-Kittel-Kasuya-Yosida (RKKY) interaction and the Kondo effect compete with each other. The RKKY interaction enhances the long-range magnetic order, while the Kondo effect quenches the magnetic moments of the localized f electrons. Most of the cerium compounds order antiferromagnetically with the Neel temperature T_N, because the RKKY interaction overcomes the Kondo effect at low temperatures.Recently, a new aspect of cerium and uranium compounds with magnetic ordering has been discovered. When a pressure P is applied to compounds with antiferromagnetic ordering such as CeCu_2Ge_2, CeIn_3, and CePd_2Si_2, T_N reaches zero at the quantum critical pressure Pc, and superconductivity is observed at around P_c. The transition from the magnetically ordered state to the nonmagnetic state under pressure, crossing the quantum critical point, is the most interesting issue in strongly correlated f electron systems.We have depeloped high pressure cells for the de Haas-van Alphen experiment and electrical resistivity measurement which can be rotated in the magnetic fields, and investigated the heavy fermion state including the pressure-induced superconductor, which are summarized as follows ;1. Discovery of the pressure-induced superconductor CeIrSi_3 and CeCoGe_3 and huge upper critical field with strong coupling behavior2. Split Fermi surface due to antisymmetric spin-orbit interaction based on the non-conetrosymmetric crystal structure in CeTX_3 (T : transition metal, X : Si, Ge).3. Pressure-induced heavy-fermion superconductivity in Ce_2Ni_3Ge_5 and CePt_3Si,4. Pressure phase diagram in a ferromagnet CePtAl and an antiferromagnet CeTl_3