MAGNETICALLY CORRELATED INTERNAL-FRICTION AND YOUNGS MODULUS IN LA(Y)-CA-MN-O PEROVSKITES

Internal friction (Q(-1)) and Young's modulus have been studied on a s eries of La1-xCaxMnO3-delta and La0.6Y0.07Ca0.33MnO3-delta polycrystal s. A Q(-1) peak originating from the changes of the magnetic entropy i s observed. The Q(-1) peak for x in the range of 0<x<0.5 can be correl ated with a transition from a paramagnetic (PM) disordered state to a ferromagnetic (FM) ordered state accompanied by a cooperative Jahn-Tel ler lattice distortion; from a PM insulator to a spin-glass insulator and accompanied with a large loss of modulus for 0.5<x<1.0; and the Q( -1) peak is ascribed to a transition from a PM to an AFM insulator for x=1.0.