Enhancement of the anomalous Nernst effect in epitaxial Fe4N films grown on SrTiO3(001) substrates with oxygen deficient layers

Abstract

Anomalous Nernst effect of epitaxial Fe4N films on MgO(001), MgAl2O4(MAO)(001), and SrTiO3(STO)(001) substrates grown by molecular beam epitaxy was investigated. Moderately large anomalous Nernst coefficients (S-ANE) of 1.4 and 1.7 mu V/K were obtained in the Fe4N films on the MgO(001) and MAO(001) substrates, respectively, and large anomalous Hall angles (similar to 0.06) and transverse thermoelectric conductivities [similar to 1.3 A/(m K)] were derived from the experimental results. On the other hand, a large effective S-ANE of 2.8 mu V/K was obtained in the Fe4N film on the STO(001) substrate. The origin of the enhanced effective SANE is the negatively large Seebeck coefficient (S-SE) in an oxygen deficient STO layer near the surface of the STO substrate. This indicates that it is possible to enhance the effective S-ANE of ferromagnetic materials by utilizing adjacent materials with large vertical bar S-SE vertical bar such as the oxygen deficient STO layer. Published under an exclusive license by AIP Publishing.