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

Pierre Ferdinand P. Poudeu

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Honore Djieutedjeu, Xiaoyuan Zhou, Hang Chi, Neel Haldolaarachchige, Kulugammana GS Ranmohotti, Ctirad Uher, David Young, and Pierre FP Poudeu (2014)

Journal of Materials Chemistry C, 2(30):6199-6210.

The ability to manipulate the electronic structure of the low-dimensional magnetic semiconductor MnSb2Se4 via 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 T-c similar to 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.

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