EPR studies for GdBa2Cu3O7-δ added with nanosized ferrite CoFe2O4

Frontiers in Theoretical and Applied Physics/UAE 2017

Basma, H.^1 ; Isber, S.^2 ; Noureldeen, S.^3 ; Anas, M.^4 ; Awad, R.^1

Physics Department, Faculty of Science, Beirut Arab University (BAU), Beirut, Lebanon^1

American University of Beirut, Department of Physics, Beirut, Lebanon^2

Physics Department, Faculty of Science, Lebanese University, Beirut, Lebanon^3

Physics Department, Faculty of Science, Alexandria University, Egypt^4

关键词: Absorption curves;    Chemical coprecipitation method;    Dipole interaction;    EPR measurements;    Increasing temperatures;    Magnetic parameters;    Nano-Sized ferrites;    Solid-state reaction techniques;   

Others  :  https://iopscience.iop.org/article/10.1088/1742-6596/869/1/012024/pdf
DOI  :  10.1088/1742-6596/869/1/012024

来源: IOP

【 摘 要 】

EPR measurements were conducted at different temperatures 100K ≤ T ≤ 295K for GdBa2Cu3O7-δsuperconducting samples prepared by the conventional solid state reaction technique, added with x wt.% nanosized ferrite of CoFe2O4, prepared by chemical co precipitation method, with 0 ≤ x ≤ 0.40 wt.%. A broad isotropic symmetric EPR line with g factor g ≈ 2 is detected for the (CoFe2O4)xGdBa2Cu3O7-δsamples, corresponding to Gd3+ions. The broadness is attributed to the superposition of signals resulting from the clustering of Gd3+ions and the dipole interaction between these ions. The analysis of the absorption curve and its first derivative allowed to obtain several magnetic parameters including the number of spins N participating in EPR resonance which showed a decrease with increasing temperature and the activation energy Ea, which experienced a decrease with x.