Donor and acceptor impurity-driven switching of magnetic ordering in MnSb2−xSnxSe4

The ability to manipulate the electronic structure of the low-dimensional magnetic semiconductor MnSb2Se4via isomorphic Sn/Sb substitutions enables independent investigation of the interactions of free carriers with localized magnetic moments and their effects on the predominant magnetic ordering in the p-type MnSb2−xSnxSe4 (0 ≤ x ≤ 0.25) semiconductors. We find a large increase in the electrical resistivity and thermopower with increasing Sn content suggesting a surprising decrease in the overall hole density. X-ray photoelectron spectroscopy reveals that Sn atoms enter the structure in the 2+ oxidation state, whereas a fraction of the remaining Sb3+ partially oxidizes to Sb5+ to maintain the electroneutrality of the compound. Therefore, we attribute the drop in the hole density to electron–hole compensation processes. Interestingly, magnetic susceptibility data reveal a remarkable switching of the dominant magnetic interaction from antiferromagnetism (AFM) (x = 0) to ferromagnetism (FM) with Tc ∼ 56 K for 0.05 ≤ x ≤ 0.15 samples and a reversal to AFM ordering for x > 0.15. The Sn-dependent FM interaction in MnSb2−xSnxSe4 is rationalized within the context of the formation of overlapping bound magnetic polarons (BMPs) through the interactions between the added electrons/holes and localized moments of Mn2+ magnetic ions.