Exchange Interactions in Mn[Sc2]S4

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Abstract
One possible explanation for the rapid development of antiferromagnetism in the system MnCr2S4–MnInCrS4 is the existence of antiferromagnetic interactions among the A‐site Mn. The normal spinel MnSc2S4 was prepared and studied to determine the actual magnitude of A‐A interactions in sulfide spinels. The cubic lattice parameter is a=10.615 Å with u=0.381. Magnetic susceptibility measurements showed this material to be an antiferromagnet with a Néel temperature below 4.2°K and with a θ‐parameter of about −21°K. The magnitude of the Mn–Mn exchange interaction was determined by fitting the susceptibility data from 15° to 295°K to the [3, 3] Padé approximant to the Rushbrooke‐ Wood series expansion. The value of the Mn–Mn exchange constant was found to be J/k=−0.80°K. The use of Padé approximants rather than the truncated series itself greatly improves the applicability of the power series expansions at temperatures comparable to or below the value of the θ‐parameter.