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Effect of cation substitution on magnetic properties in Mn 1-xA'xCr2S4 (A' = Cd, Zn) thiospinel series

Abstract:

Colossal magnetoresistance (CMR) materials such as REMnO<inf>3</inf> perovskites and AB<inf>2</inf>S<inf>4</inf> thiospinels have been well studied in the past. The authors present thiospinel compounds with A = Mn, since they may be viewed as a link to REMnO<inf>3</inf> CMR perovskites. Ferrimagnetic MnCr<inf>2</inf>S<inf>4</inf> is known to present a T<inf>c</inf> of 65 K and a magnetic transition towards a non-collinear Yafet-Kittel state. The (Mn <inf>1-x</inf>A'<inf>x</inf>)Cr<inf>2</inf>S<inf>4</inf> series (A = Cd, Zn) was synthesised at 850°C. This series crystallises in the space group Fd3m with a close to 10 Å. When A' = Cd (T<inf>c</inf> ranging from 68 K, x = 0·2, to 79 K, x = 0·6), the ferromagnetic features are enhanced, indicating that antiferromagnetism between Mn spins is progressively lost. For A' = Zn, two magnetic transitions take place, one at 15 K, which is reminiscent of the antiferromagnetic state of ZnCr<inf>2</inf>S<inf>4</inf> and another one at T<inf>c</inf> = 115 K. Impurities which could be responsible of these two magnetic states are excluded. © 2010 Institute of Materials, Minerals and Mining.