Enhancement of an iron-based layered compound superconducting properties by high pressure synthesis technique

Abstract

Here we report the high pressure synthesis technique, physical properties and effect of Y substitution on the La-based iron oxypnictide LaFeAsO 0.6 superconductor. Replacement of La3+ by Y3+ in La1-xYxFeAsO0.6 results in the decrease of lattice parameters, due to internal chemical pressure effect into the system. Superconducting transition temperature (Tc) increases up to 43.1K for x=0.5. The present results provide an alternative, much simpler way to achieve higher-Tc in the La-based oxypnictide superconductors, as well as revealing that the lattice parameters are the dominating parameter to determine Tc of these new high-Tc superconductors. Also we report the new discovery of Ca1-xNaxFe2As2 with Tc = 26 K. ©2008 The Physical Society of Japan.