Pressure tuning of spin-phonon coupling in ZnCr$_{2}$Se$_{4}$ by Raman spectroscopy

Raman scattering measurements are performed to investigate the phonon spectra of ZnCr$_{2}$Se$_{4}$ single crystal as functions of pressure and temperature. We find that five characteristic phonon modes vary simultaneously by changing pressure and temperature. With decreasing temperature, the phonon modes show anomalous shifts at $T_{\mathrm{E}}$, corresponding to the temperature of negative thermal expansion of lattice. With the application of pressure, in addition to the enhancements of frequency of Raman modes, $T_{\mathrm{E}}$ shifts to higher temperature, indicative of strengthening of spin-phonon coupling.