  The interplay of magnetism and spin-orbit coupling on an Fe kagome lattice in
Fe3Sn2 crystal produces a unique band structure leading to an order of
magnitude larger anomalous Hall effect than in conventional ferromagnetic
metals. In this work, we demonstrate that Fe-Sn nanocrystalline films also
exhibit a large anomalous Hall effect, being applicable to magnetic sensors
that satisfy both high sensitivity and thermal stability. In the films prepared
by a co-sputtering technique at room temperature, the partial development of
crystalline lattice order appears as nanocrystals of Fe-Sn kagome layer. The
tangent Hall angle, the ratio of Hall resistivity to longitudinal resistivity,
is largely enhanced in the optimal alloy composition of close to Fe3Sn2,
exemplifying the kagome origin even though the films are composed of
nanocrystal and amorphous-like domains. These ferromagnetic Fe-Sn films possess
great advantages as a Hall sensor over semiconductors in thermal stability
owing to the weak temperature dependence of the anomalous Hall responses.
Moreover, the room-temperature fabrication enables us to develop a mechanically
flexible Hall sensor on an organic substrate. These demonstrations manifest the
potential of kagome metal as an untapped reservoir for designing new functional
devices.
