Coexistence of Superconductivity and Ferromagnetism in ErRh4B4

Abstract

In this thesis work, the interplay of magnetism and superconductivity in ErRh4B4 was investigated theoretically. Starting from a model Hamiltonian developed for the system and employing the equation of motion approach of retarded Green’s function formalism, expressions which relate superconducting transition temperature (TC ), magnetic ordering temperature (Tm), superconducting order parameter (∆sc) and magnetic ordering parame ters (η) were obtined. The obtained results indicate the supression of superconductivity with increasing magnetic order. The results also revealed the supression of supercon ducting and magnetic orders with rise in temperature. Coexistence of superconductivity and magnetism was observed for the system under investigation in a small region with 0 ≤ η ≤ 1.5. This coexistence is very fascinating because it can give hint for the search of possible mechanism of pairing in these type of strange superconductors