Thermoelectric, Magnetic Properties and Re-entrant Spin-glass State in MBE Grown FeAs Film on LaAlO3(100) Substrate

We report on the growth, thermoelectric, magnetic properties, and re-entrant spin-glass state in MnP-type orthorhombic FeAs thin film, grown on LaAlO3 (100) substrate by using a molecular beam epitaxy. The film is polycrystalline with a grain size about 200 nm. Electrical resistivity as a function of temperature revealed a metallic behavior. A sign change of Seebeck coefficient was observed at 370 K, due to the contribution of multiple bands to charge transport. We found a re-entrant spin-glass state in the film, attributed to strain in the sample. As a result, a very sharp spin-glass magnetic transition at 50 K was observed in the temperature dependence of Seebeck coefficient, electrical resistivity, and magnetization curves. The bifurcation point between zero field cooled and field cooled magnetization occurred at 350 K. A ferromagnetic-type behavior was observed over a temperature range from 10 to 300 K, confirming the re-entrant spin-glass state. Where the determined magnetization and coercive field are small, around 7 emu cm(-3) and 300 Oe at 10 K, respectively. Our work provided a study on thermoelectric and magnetic properties of re-entrant spin-glass FeAs in thin film form