Crystal Structure And Mechanism Of Superconductivity In Cerium Based Heavy Fermions

Superconductivity in certain intermetallic rare-earth compounds takes place amongst it’s electron-hole elementary excitations referred to as excitons. No theoretical study has been performed taking account of these excitons. In the present attempt it has been done. Formation of Cooper pair in heavy electrons due to electron-hole interaction has been shown in our study. This knowledge is consistently used in the present investigation of bulk superconductivity in Ce-based silicons. Singlet superconducting electron-hole pairing of excitonic-type in heavy fermion system has been used to explain superconductivity, quite unlike earlier studies where conduction and felectrons and their hybridization were considered independently. It turns out that one can explain Tc = 0.6 K in CeCu2Si2 and other Ce-based silicons with tetragonal crystal structure. In these materials magnetism and superconductivity do not coexist and has nonFermi Liquid (NFL) behaviour with critical temperature Tc≈0.7K. The superconducting cooper pairs are particle having large effective masses. The tetragonal crystal CeCu2Si2 has the layers of CeSi2 separated by layers of CuSi2. Electron – hole coupling has extensively been studied in Graphene bilayer and very little on heavy fermion systems. Graphene which is one atomic layer separated from graphite crystal. The pairing of electrons and holes due to their coulomb attraction in two parallel independently gated layers separated by a barrier which is a dielectric material shows the existence of the BCS-like pair – condensed state at weak coupling. The total energy increases with increase in temperature since a sigmoid- like curve was observed. The specific heat capacity data revealed the fact that at the transition temperature, an energy gap is created at the Fermi energy level and hence there is a sudden change in the value of specific heat capacity of these heavy fermion system. The Gaussian – like curve obtained skewed to the left suggests that superconductivity is a bulk phenomenon in these compounds. At the peak, the 𝐶𝑣 was observed to be 0.4560 eV/K. The transition temperature obtained was 0.59K