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The discovery of superconductivity in CeCu2Si2 opened the field of unconventional superconductivity in strongly correlated systems. Despite more than 30 years of intensive research, the nature of the superconducting phase and of the A-phase as well as the interaction between both are very far from being understood. A major problem was the lack of large single crystals with well defined physical properties. First part of talk, I will present a detail crystal growths of various intermetallic compounds using different growth techniques along with introduction.
In the second part of my talk I will present the detail investigation of the physical properties of EuFe2As2. The parent compound show an antiferromagnetic ordering at 190 K along with structural transition related to the FeAs layers and magnetic ordering of Eu2+ moments at 20 K. We studied the effect of hole-doping, pressure and chemical pressure, by measurements of the thermoelectric power, magnetic susceptibility, specific heat and electrical resistivity. The evolution upon doping indicates the drastic changes of the electronic configuration at critical values, superconductivity emerges as the Fe ordering is suppressed. The temperature dependences of thermoelectric power and electrical resistivity observed in the normal state above the SC transition suggest deviation from Fermi liquid state . We also studied the in-plane anisotropy of the thermoelectric power and electrical resistivity by de-twinned single crystals, which suggests the electronic nematicity for under doped samples. Interestingly in EuFe2As2 one can de-twinned the crystal by external pressure or using Eu spin. In addition to this, Eu magnetism undergoes from A-type AFM to spin glass state as a function of P doping to As site. |