Ultrasonic studies on colossal magnetoresistive La1-xCaxMnO3 (x = 0.25, 0.33 and 0.45)

The colossal magnetoresistive material La1-xCaxMnO3 with x = 0.25, 0.33, and 0.45, was investigated through sound velocity and ultrasonic attenuation measurements. Lattice hardening was observed below T-c (paramagnetic-ferromagnetic transition) in x = 0.25 and 0.33 samples, indicating the prominent role of lattice vibrations in the physical properties of this material. The x = 0.45 sample also showed lattice hardening together with velocity hysteresis which is suggested to be caused by simultaneous occurrence of conducting ferromagnetic state and charge-ordered region. (C) 2003 Elsevier Science B.V. All rights reserved.