Transient differential reflectivity of ferromagnetic and paramagnetic phases in the bilayered manganite La1.24Sr1.76Mn2O7

TL;DR

This study investigates the photoinduced differential reflectivity in bilayered manganites across ferromagnetic and paramagnetic phases, revealing temperature-dependent relaxation components linked to magnetic and lattice correlations.

Contribution

It provides new insights into the transient optical responses of bilayered manganites, highlighting the coexistence of slow and fast relaxation processes related to magnetic and Jahn-Teller distortions.

Findings

Enhanced slow relaxation below Tc indicating laser heating effects.

Unconventional fast relaxation with asymmetric peak at Tc.

Fast component linked to short-range Jahn-Teller correlations.

Abstract

Photoinduced effects in a single crystal of bilayered manganites, La2-2xSr1+2xMn2O7 (x=0.38), were investigated in a wide range of temperatures by pump-probe measurement at a photon energy of 1.6eV. In a ferromagnetic metallic state, significant enhancement of positive rise in differential reflectivity with a slow relaxing time of hundred picoseconds was observed just below Tc=127K, indicating that the reflectivity change with the slow relaxation time constant is induced by laser heating. We have also observed an unconventional fast relaxing component that has a time constant of the order of ten picoseconds. This fast relaxing component, whose absolute value has an asymmetric peak at Tc, is presumably due to short-range correlation of Jahn-Teller distortion.