Mn2−xHoxSnS4: A mixed quaternary metal chalcogenide system with an antiferromagnetic ordering

Mn2SnS4 is a unique compound in the category of MII2AIVQ4 (M ​= ​3d metal, A ​= ​Gr 14 element and Q ​= ​S, Se and Te) with distinct crystal structure as well as magnetic properties. In this research article, we report synthesis and study of magnetic properties of holmium substituted (up to 10%) Mn2SnS4 compounds. From the Rietveld refinement of powder X-ray diffraction data, it is observed that Ho preferentially occupies Mn-site and there is no site disorder at Sn position. XPS study indicate that Mn, Ho and S adopt ​+ ​II, +III and –II oxidation state, respectively. To facilitate the aliovalent substitution (Ho3+ in place of Mn2+), tin adopt mixed valence, a mixture of +IV and +II state (i.e., Sn4+/Sn2+) and maintain the charge neutrality. Parent Mn2SnS4 is an antiferromagnetic compound with two magnetic transitions: i] 53 ​K (a probable spin canting induced weak ferromagnetic transition) and ii] 152 ​K (an ordered antiferromagnetic transition). Upon holmium substitution, the low temperature magnetic transition completely disappears, however, the high temperature antiferromagnetic transition is retained with ordering temperature around 150 ​K.