Exchange bias and spin glass in La2FeMnO6 nanoparticles

The aim of this work is to study the La2FeMnO6 double perovskite system from an experimental point of view. The nanoparticles were prepared through the ionic coordination reaction method and have a mean particle size of 36 nm, as determined by MEV analysis. The crystal structure is monoclinic with P21/n space group. The 57Fe Mössbauer spectroscopy (MS) study reveals that Fe ions species have a dominant magnetic spectra at temperatures smaller than 90 K, and above 180 K the spectra are dominated by a paramagnetic component. The magnetization versus temperature (MxT) measurement showed a fast increase of magnetization at temperatures below 130 K and seems to be related to the Fe moments. The M−1 × T data follows a linear trend for T > 591 K indicating a magnetic transition at this temperature. The MS and the magnetic data reveal that for T > 180 K the ferromagnetic signal is mainly due to Mn3+OMn+4 clusters. Studies on AC susceptibility as a function of frequency suggested a cluster spin glass transition at 98.9 K, and the field cooling MxH loops depicted an exchange bias effect below 20 K. Both results indicate the complexity of this system making it of great interest in basic research and practical applications.