Superconductivity in layered Ruddlesden-Popper perovskites and Iron selenide systems
ABSTRACT :
Since the accidental discovery of superconductivity in 1911 by H. Kamerlingh Onnes, there has been a wide range of superconducting compounds including the conventional BCS superconductors to the non-BCS High Temperature Superconductors. Till date there are several families of high temperature superconductors among which cuprates are the most popular ones due to its relatively high transition temperatures, reaching up to a maximum of 134 K in Hg-1223 compound at ambient conditions. Cuprate superconductors in general have layered perovskite like structure with intermediate conducting and insulating layers. There is a growing interest in probing similar layered structures for high temperature superconductivity. Following these lines, we are interested in investigating a non-cuprate based, layered Ruddlesden-Popper compounds and study its physical properties. Present work will mainly focus on layered Ruddlesden-Popper compounds namely Sr3Cr2O7 and Sr3Mo2O7, which are theoretically predicted to show superconductivity upon electron doping. Here we propose to investigate the structural and physical properties of these electron doped compounds.
Iron pnictide superconductors are another class of high temperature superconductor which are of great interest mainly due to the strong involvement of 3d-orbitals of the magnetic Fe atoms. FeSe has a simple anti-PbO type tetragonal structure with space group I4/mmm. In this work we have also carried out phase stabilization studies, assisted with modified sintering cycle followed by rapid thermal quenching, in FeSe superconductors. Here we also observe the growth of micro-sized hexagonal shaped crystallites in FeSe polycrystalline bulk.