Magneto-dielectric effect in relaxor superparaelectric Tb2CoMnO6 film

Abstract

We report magneto-dielectric properties of partially B-site ordered monoclinic Tb 2 CoMn O 6 double perovskite thin film epitaxially grown on Nb : SrTi O 3 (100) substrates by metalorganic aerosol deposition technique. Transmission electron microscopy and electron energy loss spectroscopy mapping shows the presence and distribution of both C o 2 + and C o 3 + ions in the film, evidencing a partial B -site disorder, which was further confirmed by the observation of reduced saturation magnetization at low temperatures. The ferromagnetic Curie temperature, T C = 110 K , is slightly higher as compared to the bulk value (100 K) probably due to an in plane epitaxy tensile strain. Temperature dependent dielectric study reveals an unexpected high temperature dipolar relaxor-glass-like transition at a temperature T ∗ ∼ 190 K > T C , which depends on the applied frequency and indicates a superparaelectric behavior. Two different dielectric relaxation peaks have been observed; they merge at T ∗ where likely a coupling to the disorder-induced short range charge-spin correlations results in a 4% magneto-dielectric coupling.