RESEARCH ACTIVITY

Sputtered Fe-Sn alloy films. (a) Layered Fe-Sn kagome compounds. The Fe₃Sn kagome layer is depicted in the upper side, and the layer stackings in antiferromagnetic FeSn, ferromagnetic Fe₃Sn₂ and Fe₃Sn are displayed in the lower side. (b) The device structure is shown schematically. An excitation current I was injected to an Fe-Sn film on an insulating substrate, and longitudinal voltage V_xx and transverse Hal voltage V_yx were measured. A magnetic field B is applied perpendicularly to the film plane. (c) Fe content x in Fe_xSn_1−xfilms was controlled by changing the Fe chip configuration on the Sn target. Error bars (standard deviations for x) are smaller than the symbols. A photograph when six Fe chips are placed is shown in the inset. The scale bar shows 10 mm. Blue, green, and, red broken lines correspond to x = 0.50 (FeSn), 0.60 (Fe₃Sn₂), and 0.75 (Fe₃Sn), respectively. (d) XRD patterns for Fe_xSn_1−x films with x = 0.54, 0.62, and 0.78 grown on sapphire (0001) substrates at T_g = 500 °C. The data are shifted vertically for clarity. The film thicknesses were approximately 40 nm. See the text and Supplementary Fig. S1 for the phase identification of these films. (e) XRD patterns for 40-nm-thick Fe_0.60Sn_0.40 films on sapphire, glass and, PEN sheet substrates prepared at room temperature. (f) (False color image) Cross-sectional high-resolution transmission electron microscopy image of a room-temperature sputtered Fe_0.60Sn_0.40 film on a sapphire substrate. The scale bar shows 5 nm. The inset shows a selected area electron diffraction pattern, revealing the presence of nanocrystalline domains. (From Fe-Sn nanocrystalline films for flexible magnetic sensors with high thermal stability)