High pressure study on ZnCr2S4 spinel

We have performed structural and vibrational studies on the magnetically frustrated ZnCr2S4 spinel under high pressure up to 42 GPa. The starting materials crystallize in a cubic phase with space group \textit{Fd-3m}. Upon pressure increasing, two reversible structural transitions were observed at 22 GPa and 31 GPa, respectively. The first high-presure phase is identified as a tetragonal $I$41/\textit{amd} phase, whereas the second pressure-induced transition is attributed to an orthorhombic distortion of the tetragonal cell. We also detected the presence of a secondary (minority) high-pressure phase in those high pressure phases. Careful inspection of the starting \textit{Fd-3m} phase revealed a previously unnoticed isostructural transition, which is intimately connected with changes in the electronic properties. Finally, close comparison with the behavior of relevant Cr-bearing chalcogenide spinels revealed that the \textit{Fd-3m}$\to I$41/\textit{amd} transition pressure depends on the ratio of the magnetic exchange interactions active in these systems, i.e. it appears to originate from a spin-driven Jahn-Teller effect.