Magneto-transport property of FeSe thin films prepared by selenization technique

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Magneto-transport and structural properties of FeSe thin films prepared on GaAs substrates by selenization technique were studied.(1) Fe_2Se_3/Fe/GaAs structures were prepared by a selenization of Fe films on GaAs (001) substrate. The selenization is not a deposition process, but replacing Fe atoms by Se atoms supplied as molecular beams from K-cell. The substrate temperature was 400℃ and Se beam pressure was 4×10^<-8> Torr. Fe_2Se_3 compound, which was different from bulk stable structures of Fe_3Se_4 and Fe_7Se_8, was obtained by this technique.(2) From the resistivity and Hall effect measurements, it was found that the resistivity of FeSe thin film was ρ=1.1×10^<-4> Ωm, and carrier (electron) density was n=2.1×10^<23> m^<-3>. At the relatively low field region of the applied external magnetic field in Hall effect measurement, Hall resistivity exhibited similar to the extraordinary Hall effect which was observed in typical ferromagnetic materials. Details on magneto-transport property including anisotropic feature due to the crystal structure are followed.(3) From the x-ray reciprocal space mapping measured by 2theta(omega)-psi scan, it was found that the crystal structure of Fe_2Se_3 is cubic with a=0.551 nm by fitting the Fe_2Se_3 reflections. The cubic structure of Fe_2Se_3 was easily understood by the positions of Fe_2Se_3 reflections which locate at slightly lower 2theta angles than GaAs reflections. Both of Fe_2Se_3 (022) and (113) reflections which belong to different reflection planes in the reciprocal space were detected simultaneously. This indicated that Fe_2Se_3 cubes are not oriented in-plane direction of the layer.