Improving the surface structure of high quality Sr2FeMoO6 thin films for multilayer structures

Two sets of Sr2FeMoO6 thin films were prepared with pulsed laser deposition and the effect of the laserfluence and the deposition temperature was investigated. The Sr2FeMoO6 thin films showed clear evi-dence of impurity phases when the laser fluence was altered. Phase pure films resulted through thewhole temperature range between 900 ◦C and 1050 ◦C when a proper laser fluence was used. Films fabri-cated at lower deposition temperatures resulted with smaller surface roughnesses around 5 nm, higherCurie temperatures and with relatively high saturation magnetization values. The Curie temperaturewas determined from the minimum of the first order derivative and results showed the highest values of350 K and above. The films with the highest Curie temperature reached zero magnetization above 400 K.The results indicate that both high microstructural and high magnetic quality Sr2FeMoO6 thin films canbe obtained with a deposition temperature between 900 ◦C and 950 ◦C. This provides better fabricationparameters for the upcoming SFMO multilayer structures.</p

28th International Conference on Low Temperature Physics (LT28) 9–16 August 2017, Gothenburg, Sweden

Pulsed laser deposited Sr2FeMoO6 thin films were investigated for the first time with scanning tunneling microscopy and spectroscopy. The results confirm atomic scale layer growth, with step-terrace structure corresponding to a single lattice cell scale. The spectroscopy research reveals a distribution of local electrical properties linked to structural deformation in the initial thin film layers at the film substrate interface. Significant hole structure giving rise to electrically distinctive regions in thinner film also seems to set a thickness limit for the thinnest films to be used in applications.</p

Thickness dependent properties of SFMO thin films grown on STO and LSAT substrates

Pure, fully textured and c-axis oriented Sr2FeMoO6, films were deposited on SrTiO3 and (LaAlO3)(0.3)(Sr2AlTaO6)(0.7) substrates with different thicknesses. A decrease in substrate induced strain was observed in films on SrTiO3 with increasing thickness, but the strain in the films on (LaAlO3)(0.3)(Sr2AlTaO6)(0.7) was nearly constant within the whole film thickness range. Despite the differences in the strain, the magnetic properties of the films showed similar thickness dependence on both substrates. The saturation magnetization and Curie temperature increased until around 150 nm thickness was reached. Semiconducting low temperature upturn in resistivity was observed in all the films and it was enhanced in the thinnest films. Thus, the band gap energy increases with increasing film thickness. According to these results, at least 150 nm thickness is required for high quality Sr2FeMoO6 films.</p

Thickness Dependent Properties of Sr2FeMoO6 Thin Films Grown on SrTiO3 and (LaAlO3)0.3(Sr2AlTaO6)0.7 Substrates

Pure, fully textured and c-axis oriented Sr2FeMoO6 films were deposited on SrTiO3 and (LaAlO3)0.3(Sr2AlTaO6)0.7 substrates with different thicknesses. A decrease in substrate induced strain was observed in films on SrTiO3 with increasing thickness, but the strain in the films on (LaAlO3)0.3(Sr2AlTaO6)0.7 was nearly constant within the whole film thickness range. Despite the differences in the strain, the magnetic properties of the films showed similar thickness dependence on both substrates. The saturation magnetization and Curie temperature increased until around 150 nm thickness was reached. Semiconducting low temperature upturn in resistivity was observed in all the films and it was enhanced in the thinnest films. Thus, the band gap energy increases with increasing film thickness. According to these results, at least 150 nm thickness is required for high quality Sr2FeMoO6 films.Peer reviewe

Toward Versatile SFMO Based Spintronics by Exploiting Nanoscale Defects

To actualize the high spintronic application potential of complex magnetic oxides, it is essential to fabricate these materials as thin films with the best possible magnetic and electrical properties. Sr2FeMoO6 is an outstanding candidate for such applications, but presently no thin film synthesis route, which would preserve the magnetic properties of bulk Sr2FeMoO6, is currently known. In order to address this problem, we present a comprehensive experimental and theoretical study where we link the magnetic and half metallic properties of Sr2FeMoO6 thin films to lattice strain, Fe—Mo antisite disorder and oxygen vacancies. We find the intrinsic effect of strain on the magnetic properties to be very small, but also that an increased strain will significantly stabilize the Sr2FeMoO6 lattice against the formation of antisite disorder and oxygen vacancies. These defects, on the other hand, are recognized to drastically influence the magnetism of Sr2FeMoO6 in a nonlinear manner. On the basis of the findings, we propose strain manipulation and reductive annealing as optimization pathways for improving the spintronic functionality of Sr2FeMoO6