Novel phases at magnetic instability and multipolar ordering

Un-conventional superconductors provide important opportunities to investigate the interplay between magnetism and superconductivity. CeCu2Si2 is a classical heavy fermion superconductor, in which the existences of a magnetic phase adjacent to the superconducting phase. The first part of my presentation includes general introduction on novel phases at magnetic instability and 4f-electrons in solids. Then, I introduces various technique of crystal growth including flux method, self flux, Bridgman technique and optical furnace with different compound I grown. Second part of my presentation on the detail investigation of the magnetic properties of the YbRu2Ge2 compound, which crystallizes in the tetragonal structure. magnetic susceptibility, specific heat and resistivity were investigated on a single crystals shows the multiple ordering at around 5.5 K and 6.5K, and a further one at 10K with quasi quartet CEF ground state. There is a clear evidence for magnetic ordering below 6.6 K from micro-SR and neutron measurements, but do not reveal any dipole ordering below 10K. The results are discussed in terms of quadrupolar ordered and magnetically ordered states.