EPR study on higher oxygen pressure synthesized compound Pr2−xGdxCuO4

Abstract The electron paramagnetic resonance (EPR) and magnetic susceptibility measurements were performed in Pr 2− x Gd x CuO 4 (x=0.02; 0.05) annealed at the higher oxygen pressures of 15 and 21 bar. This annealing treatment causes a reduction of about 8% in the second order crystalline electric field (CEF) parameter | b 2 0 | at the Gd 3+ site and leads to a drastic broadening of the Gd 3+ resonance lines, which is consistent with spin relaxation processes of Gd 3+ due to the first excited state of Pr 3+ , an increase in the CEF inhomogeneity upon doping and annealing, and an existence of Pr ions in both 3 + and 4 + oxidation states. The exchange coupling constants j Pr−Pr and j Gd−Pr are also estimated.