Controllable Broadband Absorption in the Mixed Phase of Metamagnets

Combination of neutron scattering, muon spin relaxation, specific heat, ac and dc magnetization measurements, and electron magnetic resonance, reveals the ability of metamagnetic materials to absorb the electromagnetic radiation in an extremely broad frequency range. The effect is controlled by the external magnetic field, which actuates a mixed ferro/antiferromagnetic phase, where the absorption in Cu₃Bi(SeO₃)₂O₂Br system extends over at least nine order of frequency scale. Considering that artificial metamagnets (magnetic multilayers) allow for a direct control over the required magnetic field, a novel way of tuning the material's functional properties is imminent. The work is performed in the LNS and LMU laboratories of NUM and in the Jožef Stefan Institute (Slovenia) in close collaboration with partners from Germany and Moldova.