ESR study of the impurity-induced antiferromagnetic ordering in the diluted spin-Peierls magnet CuGeO3

A detailed ESR study of the microscopic phase separation occurring at the impurity-induced magnetic ordering in the diluted CuGeO3 is performed. A dependence of the paramagnetic fraction below the transition temperature on the applied magnetic field is observed. The line shape above the ordering temperature is found to deviate from the single-lorentzian from up to T∼2TN. These findings are explained qualitatively by considering clusters of staggered magnetization formed around the impurity