Insulator-to-metal transition and large thermoelectric effect in La1−xSrxMnAsO

We report the effect of Sr substitution in an antiferromagnetic insulator LaMnAsO by the measurements of electrical resistivity, Hall coefficient, Seebeck coefficient and magnetization. Upon Sr doping to its limit x~0.10, the room temperature resistivity drops by five orders of magnitude down to ~0.01Ω·cm, and the temperature-dependent resistivity shows essentially metallic behavior. Hall and Seebeck measurements confirm consistently that the insulator-to-metal transition is due to hole doping. The room temperature Seebeck coefficient for the metallic samples is as high as ~240 μ V/K, making the system a possible candidate for thermoelectric applications.