Abstract
A metastable phase α-FeSi2 was epitaxially stabilized on a silicon substrate using pulsed laser
deposition. Nonmetallic and ferromagnetic behaviors are tailored on α-FeSi2 (111) thin films, while the
bulk material of α-FeSi2 is metallic and nonmagnetic. The transport property of the films renders two
different conducting states with a strong crossover at 50 K, which is accompanied by the onset of a
ferromagnetic transition as well as a substantial magnetoresistance. These experimental results are
discussed in terms of the unusual electronic structure of α-FeSi2 obtained within density functional
calculations and Boltzmann transport calculations with and without strain. Our finding sheds light on
achieving ferromagnetic semiconductors through both their structure and doping tailoring, and provides an
example of a tailored material with rich functionalities for both basic research and practical applications.
