Evidence of structural evolution in Sr2RhO4 studied by time-resolved optical reflectivity spectroscopy

We investigate ultrafast dynamics from photoinduced reflectivity of Sr2RhO4 by using femtosecond near-infrared pulses. We observe a clear temperature dependent anomaly in its electronic dynamics which slows down below T-S similar to 160 K. In addition, coherent oscillations of the 5.3 THz A(1g) phonon exhibit a 90 degrees. shift in its initial phase across TS, indicating a structural change in octahedral rotation distortions. We propose that octahedral structure in Sr2RhO4 evolves around T-S, and it can influence the nonequilibrium dynamics of photo-induced carriers as well as realtime phonon responses. ©2019 American Physical Society11sciescopu