Raman Evidence for Symmetry Breaking in SrCr$_{2}$O$_{4}$*

Raman spectra from 400 cm$^{-1}$ to 650 cm$^{-1}$ were acquired from single crystalline SrCr$_{2}$O$_{4}$ to probe magneto-elastic effects on its frustrated magnetism. The compound contains two-dimensional sheets of CrO$_{2}$, where spin-3/2 Cr atoms with direct exchange interactions form a distorted triangular lattice with helical magnetic order below 43K [1]. Even in the paramagnetic phase, the spectra show mode splitting beyond predictions for space-group P$_{mmn}$ that describes powder x-ray diffraction data. This splitting occurs at the 480 cm$^{-1}$ A$_{g}$ mode and is enhanced below T$_{N}$, which suggests it may be associated with magneto-elastic effects. \\[4pt] [1] S E Dutton, E Climent-Pascual, P W Stephens, J P Hodges, A Huq, C L Broholm, and R J Cava, J. Phys.: Condens. Matter 23 (2011) 246005