Thermopower peak in phase transition region of (1-x)La$_{2/3}$Ca$_{1/3}$MnO$_{3}$/xYSZ

TL;DR

This study investigates how adding YSZ affects the thermoelectric power and magnetic transition in LaCaMnO3 composites, revealing a peak in thermopower linked to magnetic structure changes caused by lattice strain.

Contribution

It demonstrates the emergence of a thermopower peak in LCMO/YSZ composites during phase transition, attributed to magnetic structure variation from lattice strain effects.

Findings

TEP peak appears in composites with YSZ, not in pure LCMO.

Lattice strain from YSZ boundary layers influences magnetic structure.

Transition width correlates with magnetic susceptibility derivative.

Abstract

The thermoelectric power (TEP) and the electrical resistivity of the intergranular magnetoresistance (IGMR) composite, (1-x)La$_{2/3}$Ca$_{1/3}$MnO$_{3}$/xYSZ (LCMO/YSZ) with x = 0, 0.75%, 1.25%, 4.5%, 13% 15% and 80% of the yttria-stabalized zirconia (YSZ), have been measured from 300 K down to 77 K. Pronounced TEP peak appears during the phase transition for the samples of x $>$ 0, while not observed for x = 0. We suggest that this is due to the magnetic structure variation induced by the lattice strain which is resulting from the LCMO/YSZ boundary layers. The transition width in temperature derived from $d\chi/dT$, with $\chi$ being the AC magnetic susceptibility, supports this interpretation.