Terahertz dielectric properties of Fe 3 O 4 thin films deposited on Si (100) substrate

Fe 3 O 4 is considered to be a promising material for terahertz spintronic applications as well as for stealth technology. However, the optical properties of Fe 3 O 4 in the thin film form at terahertz frequencies are not reported in literature. In this article, we present the frequency and temperature dependence of dielectric permittivity ( ε 1 ) and optical conductivity ( σ 1 ) of Fe 3 O 4 films deposited on Si substrate. The σ 1 of these films show absorption peaks related to charge localization and shallow impurities. It is also observed that the Fe 2 O 3 /Fe 3 O 4 composite films have large σ 1 and ε 1 indicating their potential use for stealth technology applications. The overall optical properties are found to depend strongly on the microstructure and defects, such as, the grain size and the presence of grain boundaries, anti-phase boundaries, strain disorder due to lattice mismatch and/or the Fe +2 /Fe +3 ratio.