Anomalies in elastic moduli and ultrasonic attenuation near ferromagnetic transition temperature in La_0.67Sr_0.33MnO₃ perovskite

Abstract

In order to examine the existence of the metal–insulator transition, structural transition and magnetostriction effect, ultrasonic velocities and attenuation measurements have been made on La_0.67Sr_0.33MnO₃ perovskite manganite material over a wide range of temperatures from room temperature (298 K) to 460 K. The variations with temperature of the longitudinal modulus, shear modulus, bulk modulus and Young's modulus have also been determined. A dramatic softening in sound velocities and elastic moduli near paramagnetic (PM) to ferromagnetic (FM) phase transition has been noticed, which is accompanied by a peak in attenuation. The present studies have been used to explain the existence of a strong electron–phonon interaction, which arises due to the JahTeller effect, and also the evidence for the spin–phonon interaction due to the linear magnetostriction effect.