Zener relaxation in manganites?

Abstract

We conducted internal friction (IF) and elastic modulus measurements on several manganites in the temperature range 100-500 K. The La1-xCaxMnO3 series, with x=0, 0.1, 0.2, 0.33 and 1, was studied showing the magnetic phase transitions and two additional IF peaks around 320 and 400 K, respectively. Both, peaks associated to relaxations, present activation enthalpies of 2-3 and 3-6 eV, whose intensity depends on x. In this work we associate the 400 K IF peak to a Zener relaxation of the cations that occupied the same crystallographic site. We believe that the 320 K IF peak is due to different crystalline states of the samples.