摘要
The effects of rare earth site doping on the structural,superconducting and magnetic properties of SmFeAsO_(0.7)F_(0.3) iron pnictide are investigated.Gd^(3+)and Ce^(3+)ions are chosen by virtue of their position being on either side of Sm^(3+).Doping of both smaller(Gd^(3+))and larger(Ce^(3+))ions at the Sm^(3+)site increases the T_(C) up to 55 K.Doping with the smaller Gd^(3+)results in lattice contraction and thereby enhances T_(C).It is interesting to observe that though Ce^(3+)doping in SmFeAsO_(0.7)F_(0.3) exhibits an increase in lattice parameters,a substantial enhancement of T_(C) occurs.The enhancement in T_(C) due to increased charge carrier concentration is also confirmed using Hall Effect measurement.Apart from T_(C) enhancement,the simultaneous doping of both at oxygen and rare earth sites prominently increases the superconducting properties such as J_(C),H_(C1) and H_(C2).The co-doped samples also exhibit better magnetic field dependence of J_(C) over the entire field of study.It is also observed that the Ce^(3+)doped sample shows higher J_(C) in the high field region due to its enhanced flux pinning properties.
基金
the Department of Science&Technology(DST)and CSIR 12th Five Year Plan Project,“Sustainable technologies for the Utilization of Rare Earths(SURE),”(no.CSC0132)for financial support.
