High field transport and magnetic properties of RECo(P/As)O

Abstract

We report the structural, electrical and magnetic properties of Co-based layered RECo(P/As)O (RE = La, Nd, Sm) oxypnictide compounds. Cobalt shows the itinerant ferromagnetic state in these compounds. The LaCo(P/As)O shows paramagnetic (PM) to ferromagnetic (FM) transition, however in the same structure NdCo(P/As)O and SmCo(P/As)O show the PM-FM-AFM transition. The transition temperatures are dependent on both, the rare earth and the pnictogen. The transition of Co spins from FM to AFM, for magnetic Nd and Sm is both field and temperature dependent. NdCo(P/As)O and SmCo(P/As)O shows the unusual upside step like turn in resistivity. This upturn appears in NdCo(P/As)O in zero field whereas in SmCo(P/As)O with field. © 2012 American Institute of Physics.