Connection of thermopower, magnetothermopower with resistivity and magnetoresistance in manganites with Nd and Sm

Abstract

Thermopower, magnetothermopower resistivity and magnetoresistance of single crystal samples Re(1-x)SrxMnO3 (0 ≤ x ≤ 0.3, Re = Nd, Sm) were studied in wide temperature interval, included the Curie temperature TC. Giant maxima of resistivity and thermopower, very big negative magnetothermopower and magnetoresistance were found in TC region. So, a giant maximum of thermopower in TC was found, which suppressed by magnetic field. Simultaneous magnetic field destroys magneto-impurity states – ferrons as evidenced the maxima resistivity and magnetoresistance in TC Hence it follows that giant thermopower in manganites are produced by ferrons and its value is set by the quantity of impurities, that is the concentration of impurities and the volume of sample.