Development of an integrated cryogenic diamond anvil cell for photoluminescence of CrSBr.

We present the design and calibration of a cryogenic adapter for a diamond anvil cell (DAC) that enables optical spectroscopy under simultaneous low temperature and high pressure conditions. What differentiates our design from prior efforts is the straightforward construction and opportunity for rapid implementation using common cryogenic hardware. The motivation for this development work arose from room temperature photoluminescence measurements of CrSBr, a chalco-halide that exhibits strong quenching of the emission intensity on approach to the pressure-induced transition near 7.6 GPa. Normalized spectra reveal reversible red and blue shifts of the broad emission band with compression and decompression, consistent with pressure-tuned changes in the inter-layer interactions. To host such measurements, the cryo-DAC adapter provides thermally stable cryogenic operation (with either liquid nitrogen or helium) while maintaining optical access and precise pressure calibration. These measurements demonstrate that compression suppresses exciton-phonon coupling in CrSBr. Construction details, required instrumentation, pressure calibration using ruby fluorescence and temperature control are described. Typical cryogen consumption is 4-5 liters per run.