Magnetic Properties and the Effect of Exchange Bias of the Hysteresis Loop in Iron Borate Single Crystals Doped with Cobalt Ions

A combination of experimental methods has been applied to study the structure and properties of new magnetically ordered (Fe,Co)BO 3 single crystals synthesized from a high-temperature melt solution. It has been established that the (Fe,Co)BO 3 crystals are isostructural to FeBO 3 iron borate. It has been shown that even a low cobalt concentration significantly changes the magnetic properties of the crystals compared to FeBO 3 . The most pronounced feature of the (Fe,Co)BO 3 crystals is the appearance of field and temperature hysteresis of the magnetization, as well as an exchange bias of the hysteresis loop. A mechanism for the formation of these anomalous properties is proposed, associated with the formation of superparamagnetic nanoclusters containing cobalt ions in the structure of the (Fe,Co)BO 3 single crystals.