Magneto-thermopower of parent compound LaFeAsO

Abstract

We report the effect of magnetic field on the transport properties of polycrystalline parent compound LaFeAsO. The magnetic field has no significant influence on the structural phase transitions or spin density wave (SDW) ordering of small moments on iron, but causes large positive magento-resistance below 100 K. Meanwhile, the absolute magnitude of thermopower, which is negative, increases remarkably with increasing magnetic field below 100 K. Such a large positive magneto-thermopower was first reported in this iron arsenide. The result suggests that there could exist an enhancement of SDW gapping in holelike Fermi surface.