Structural and magnetic properties of S = 3/2 chemically disordered perovskite Sr2TiMnO6

Abstract: Single phase polycrystalline sample of perovskite Sr2TiMnO6 (STMO) has been successfully synthesized via solid state reaction route. Its detailed structural and physical properties have been studied using x-ray diffraction, transmission electron microscopy, magnetization, specific heat, and dielectric measurements. Rietveld analysis of the powder XRD data and transmission electron microscopy studies confirm that STMO is not a double perovskite structure with Fm-3m space group. But it is a disordered perovskite structure with Pm-3m space group where Ti4+ and Mn4+ ions are randomly distributed at the 1b site. The dc magnetization (\c{hi}dc-vs-T) measurements in the temperature range 2-300K reveals a single anomaly at ~13K with predominant long range canted antiferromagnetic (AFM) ordering. The frequency invariant maxima at 13K in the ac susceptibility (\c{hi}ac-vs-T) discards the spin-glass behaviour in STMO. Despite the presence of sharp feature in M-T data, the specific heat data (Cp-vs-T) shows only a broad hump around 13K, which has been attributed to the magneto-structural ordering giving rise to canted AFM state in chemically disorder STMO. Matching with the magnetic and specific heat anomaly, the dielectric permittivity also shows a broad anomaly around 14K, indicating the possible magneto-dielectric coupling in STMO.