The variable temperature optical reflectivity studies between 350 -10 K in cooling and heating modes show significant and reversible changes in the spectra with temperature (Figure ). The change was observed when the thermal variation of reflectivity was displayed by plotting the absolute reflectivity value at 650 nm as a function of temperature (Figure ), where a stable regime at low temperature (below 200 K) and a second regime at higher temperature was observed, suggesting a spin-state switching between two stable states (HS to LS).