Terahertz magneto-optical response in ferromagnetic Fe–Co–Al alloys

Abstract

We study the magneto-optical properties of Fe–Co–Al ordered alloys in the terahertz range of frequencies. Using the standard Kubo-based approach to compute intrinsic part of the σxy(ω) we find a strong dependence of σ xy on ω in the terahertz range. For example, we find that below 10 THz Co3Al has nearly constant σ xy and that above 10 THz it is reduced by about 50 times. Furthermore, we find a strong dependence of σ xy on the chemical composition. For example, we find that the addition of Al to Fe changes the sign of σ xy , while the addition of Co to Fe leads to a nonmonotonic dependence of σ xy on Co concentration.