Thermopower peak in phase transition region of (1−x)La2/3Ca1/3MnO3/(x)yttria-stabilized zirconia

The thermoelectric power (TEP) and the electrical resistivity of the intergranular magnetoresistance composite (1−x)La2/3Ca1/3MnO3/(x)yttria-stabilized zirconia (YSZ) (LCMO/YSZ) with x=0%, 0.75%, 1.25%, 4.5%, 13%, 15%, and 80% of YSZ have been measured from 300 down to 77 K. A pronounced TEP peak appears during phase transition for samples with x>0, while it is not observed for x=0. We suggest that this is due to the magnetic structure variation induced by lattice strain which is a result of the LCMO/YSZ boundary layers. The transition width in the temperature derived from dχ/dT, with χ the ac magnetic susceptibility, supports this interpretation.