Temperature and fluence dependence of ultrafast phase separation dynamics in Pr0.6Ca0.4MnO3 thin films

TL;DR

This study investigates how temperature and laser fluence influence the formation and dynamics of a photoinduced ferromagnetic metallic phase in strained Pr0.6Ca0.4MnO3 thin films, revealing strain-independent timescales and fluence effects.

Contribution

It provides new insights into the strain-dependent formation of transient phases and their dynamics in manganite thin films under ultrafast optical excitation.

Findings

TFM phase forms below ~60K and ~40K in different strain conditions

Cluster sizes and photomodulation depend on strain at low fluence and temperature

Characteristic timescale for phase photomodulation is strain independent

Abstract

Temperature and fluence dependence of the transient photoinduced reflectivity and the magnetooptical Kerr angle was measured in two Pr0.6Ca0.4MnO3 thin films subject to tensile and compressive substrate-induced strain. A photoinduced transient ferromagnetic metallic (TFM) phase is found to form below ~60K and ~40K in the substrate-strained and substrate-compressed film, respectively. From the hysteresis loops a difference in the TFM cluster sizes and amount of photomodulation is observed at low temperatures and low excitation fluences in the films with different strain. Surprisingly, the characteristic timescale for the TFM phase photomodulation is virtually strain independent. At high excitation fluences, the cluster sizes and amount of photomodulation are independent on the substrate-induced strain.