Thermoelectric power of hole-doped manganites: La2-2xSr1+2xMn2O7 (0.3 <= x<= 0.5) - art. no. 092407

We have investigated the hole doping effect on the thermoelectric power (S) of double layered manganites, La2 - 2xSr1 + 2xMn2O7, with nominal hole con centrations of x = 0.3, 0.4, and 0.5. A systematic change in the values of thermoelectric power was observed in the high-temperature range where sampl es were found to be paramagnetic and insulating. At low temperatures, not o nly the magnitude of S but also its temperature and magnetic-field dependen cy was found strongly influenced by a variation in x, reflecting the change s in their magnetic structures and the consequential charge-spin and charge -orbit coupling effects.