Anantharaman, M R; Sagar, S; Ganesan, V; Joy, P A; Senoy, Thomas; Liebig, A; Albrecht, M(IOP Publishing LTD, July 30, 2010)
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Abstract:
Manganites belonging to the series Gd1−xSrxMnO3 (x=0.3, 0.4 and 0.5) were
prepared by wet solid-state reaction and their thermoelectric power was evaluated. Thermoelectric
power measurements revealed a peak value at ∼40 K. All the samples exhibited a colossal
thermopower at ∼40K and in that Gd0.5Sr0.5MnO3 exhibited a maximum value of ∼35mV/K,
which is the largest reported for these class of materials at this temperature. Temperaturedependent
magnetisation measurements showed that the samples exhibit a phase transition from
paramagnetic to spin-glass–like state at these temperatures. Plausible mechanisms responsible for
the observed colossal thermoelectric power in Gd-Sr manganites are discussed