Magnetic domains and field-induced transitions in nanosized ErCo0.5Mn0.5O3

In Er(Co,Mn)O3 an avalanche mechanism occurs under the application of moderate magnetic fields, leading to the rotation of the ferromagnetic domains in one or more steps, depending on the rate of variation of the applied field. In order to deeply investigate the influence of the microstructure, we have elaborated nanosized ErMn0.5Co0.5O3 compound by a citrate method, prepared at 700 0C and further calcined at increasing temperatures which assure the formation of very reactive grains of small size (∼25 nm) and facilitate their full oxidation. Grains progressively grow from 20-30 nm up to several hundred nm, reaching good percolation at 950 0C (100 nm average size) for which a sudden jump is observed in the magnetization cycles M(H). We have simulated domains rotation by freezing a gel-type solution prepared from nanosized grains, orienting the individual spins on the paramagnetic state and subsequently freezing the gel to form single ferromagnetic domains.