Spin-driven symmetry breaking in the frustrated fcc magnet MnS2

Simon A. J. Kimber1, ∗ and Tapan Chatterji2 

1European Synchrotron Radiation Facility (ESRF), 6 rue Jules Horowitz, BP 220, 38043 Grenoble Cedex 9, France

2 Institute Laue Langevin (ILL), 6 rue Jules Horowitz, BP 220, 38043 Grenoble Cedex 9, France.

(Dated: January 12, 2015)


Abstract

We report the characterisation of natural samples of the cubic pyrite mineral MnS2 using very high resolution synchrotron X-ray diffraction techniques. At low temperatures we find a new low temperature polymorph, which results from coupling between magnetic and lattice degrees of freedom. Below the magnetic ordering temperature TN = 48 K, we detect a pseudo-tetragonal distortion with a tiny c/a ratio of 1.0006. The structure can be refined in the space group Pbca The symmetry lowering reduces magnetic frustration in the fcc Mn2+ lattice and is likely responsible for the previously reported lock-in of the magnetic propagation vector. This behaviour is similar to the frustration driven symmetry breaking reported in other three-dimensional Heisenberg magnets like the chromate spinels. 

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http://arxiv.org/pdf/1501.02129.pdf