Magnetoelectric coupling in multiferroic Tb-doped BiFeO3 nanoparticles

Bi1-xTbxFeO3 nanoparticles (x=0, 0.05, 0.10 and 0.15) of size 30-39 nm, have been synthesized by the sol-gel technique. The effects of nano-size and Tb-doping on structural, magnetic and magnetoelectric coupling (ME) have been reported. Crystallographic analysis reveals the structural transition from rhombohedral (R3c) to orthorhombic (Pn2(1)a) phase, i.e. polar-to-polar phase, with Tb-doping. The synthesized nanoparticles exhibit ferromagnetic behavior, and, the 15% Tb-doped BiFeO3 nanoparticles possess large magnetic saturation, 2.92 emu/g. The dynamic lock-in technique has been used to measure longitudinal (L-alpha(ME)) and transverse (T-alpha(ME)) ME coefficients. It has been found that both L-alpha(ME) and T-alpha(ME) increase quickly with increase in bias magnetic field, and attain maximum value, L-alpha(ME)=11.01, 10.35, 11.92, 13.18 mV/cm Oe and T-alpha(ME)=6.81, 6.85, 6.88, 7.86 mV/cm Oe, respectively, for x=0, 0.05, 0.10, and 0.15. The observed ME effect has been explained on the basis of quantum confinement, exchange interactions, spin-exchange constriction, and magnetostriction effect. (C) 2013 Elsevier B.V. All rights reserved.