Cluster glass vs. Multiferroic state in MnSb₂Se₄

In the last few decades, the quaternary and ternary transition-metal chalcogenides, having low crystal symmetry, have become a rich playground for independently organized investigations of magnetic exchange and electronic transport interactions in magnetic semiconductors. Among the known quaternary transition-metal chalcogenides, the transition-metal chalcogenide family AB₂X₄; (A = Fe, Mn; B = Sb, Bi, and X = S, Se) exhibits diverse crystal structures, where the A-site cation connectivity ranges from 1 to 3 D, depending on B-site cations, and anions. Among these compounds, MnSb₂Se₄ crystallizes in a monoclinic space group C2/m and orders antiferromagnetically below T_N = 22.5 K. In addition, careful analysis of the x-ray diffraction revealed the presence of antisite disorder (∼ 19 %) between Mn and Sb sites. As we know, antisite disorder can be a significant parameter in determining the ground state of a magnetic material. In this talk, I’ll be talking about the impact of antisite disorder on the magnetic ground state of MnSb₂Se₄.



We have prepared MnSb₂Se₄ samples with different antisite disorders by controlling the cooling rate of the furnace. The sample S1 with the lower disorder (∼ 28 %) shows quasi-one-dimensional magnetism and exhibits type-II multiferroicity below 22.5 K [1]. The sample S2 with the higher disorder (∼ 40 %) shows a cluster-glass state supported by various DC and AC magnetization measurements. A striking observation is a colossal magnetoresistance in sample S2, which was absent in S1. Interestingly, the origin of colossal magnetoresistance is not a double exchange mechanism, as heterovalency has been ruled out by electric spin resonance (ESR) measurements. The presence of colossal magnetoresistance can be attributed to competition between various magnetic states, which adds MnSb₂Se₄ to the list of a handful of materials that do not belong to the manganite family, but still show negative colossal magnetoresistance.