The group investigates magnetic properties of 4f- and 5f-electron compounds with particular interest in the heavy-electron (heavy-fermion) systems, using very-low-temperature experimental techniques and microscopic measurements such as neutron scattering and muSR. The heavy-electron systems are the inter-metallic compounds which contain elements of the rare earths (Ce, Pr, Yb, etc.) or actinides (U, Np, etc.) and behave as Landau’s Fermi liquids with quasiparticles whose effective masses are two to three orders of magnitudes larger than in ordinary metals. Such electronic states basically result from the hybridization effects that couple the 4f- or 5f- orbital levels of the lanthanide or actinide ions with the conduction states. A blend of this “c-f hybridization” and characteristics of local f orbits in compounds leads to a wide variety of non-trivial aspects of strongly correlated electrons at low temperatures. The heavy-electron compound was first recognized in CeAl3 in 1975 [1], and drew the interests of many physicists by the discovery of superconductivity in CeCu2Si2 four years later [2]. Since then, this research field has been providing a vast amount of new interesting materials and physics, most of which still deserve further investigations. Research on the heavy-electron compounds by our group started 1987, and presently focuses on the issues expressed by the keywords: weak antiferromagnetism, hidden order, anisotropic superconductivity, non-Fermi-liquid behavior, quantum criticality, quadrupole order, metamagnetism, etc.
　[1] K. Andres, J.E. Graebner, and H. R. Ott, Phys. Rev. Lett. 35 (1975) 1979.
　[2] F. Steglich, J. Aarts, C.D. Bredl, W. Lieke, D. Meschede, W. Franz, and J. Schafer, Phys. Rev. Lett. 43 (1979) 1892.