Concentration dependence of the exchange interaction in lead europium sulfide nanocrystals

Exchange interactions in nanocrystalline forms of the dilute magnetic semiconductor lead europium sulfide (PbxEuyS), as a function of europium concentration, were investigated using low temperature, high magnetic field vibrating sample magnetometry. The results were fitted to an expression containing a modified Brillouin function, which characterized the response of isolated magnetic europium ions and ion pair interactions. The pair exchange constant JpkB depended weakly on the europium content y. This property may be explained by the existence of larger clusters of Eu2+ ions in PbxEuyS nanocrystals, with the number of clusters increasing with europium content.

► First characterization of the magnetic properties of lead europium sulfide nanocrystals.
► Successful tuning of the magnetic exchange interaction in PbxEuyS as a function of europium content.
► Evidence of higher order Eu2+ ion interactions (such as doublet interactions) within the nanocrystals.