Optical nonlinearity in multiferroic bismuth ferrite

Abstract

Bismuth ferrite (BFO) nanoparticles were synthesized via sol-gel route with malic acid as a chelating agent. Structural characterization by XRD reveals the formation of single phase rhombohedral BFO and FTIR (433, 546 cm−1) confirms the molecular structure. FESEM exhibits an agglomerated spherical morphology with an average particle size of 119 nm. The first and second order structural transitions have been detected at 821 (rhombohedral – orthorhombic) and 932 °C (orthorhombic – cubic) by DTA. Strong visible light absorption with a band gap of 1.92 eV and defect related emissions at blue (417,450 nm) and green (521 nm) regions have been observed. Multiferroic properties at room temperature show weak ferromagnetism with remnant magnetization (Mr) 0.179 emu/gm and ferroelectric behavior with remnant polarization (Pr) 0.08 μC/cm2. Dielectric measurements as a function of frequency (100 Hz–5 MHz) and temperature (30–450 °C) illustrate an evidence for magnetoelectric coupling with a peak at 350 °C indicating the magnetic phase transition. Third order nonlinear optical property studied by the open aperture Z-scan technique (Nd: YAG, 532 nm, 5 ns) shows the reverse saturable absorption (RSA) based optical limiting behavior.