Exchange Interactions in Mn[Sc2]S4

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.