Effect of cation substitution on electrical conduction of the n-type ZnxSnyCrzSe4 spinels

The electrical and magnetic measurements showed that the Zn0.93[Cr1.95Sn0.05]Se4 and (Zn0.87Sn0.048)Cr2.02Se4 spinels are n-type semiconductors and antiferromagnets with the Néel temperature of 18.6 and 19.8 K, respectively. The (Zn0.87Sn0.048)Cr2.02Se4 spinel has both higher effective magnetic moment and electrical conductivity, and lower activation energy in comparison with the Zn0.93[Cr1.95Sn0.05]Se4 one. It means that in the latter case the non-magnetic Sn ions (spin defects) in the octahedral coordination cause a narrowing of the majority spin t2g orbital of the Cr3+ band leading to the lowering of the Fermi level accompanied with an increase of an energy gap. Comparable values of the Néel and Curie-Weiss temperatures in both cases suggest that the small content of the substituted Sn ions (5%) does not significantly influence on strength of the long- and short-range magnetic interactions.