Ferromagnetic and dielectric behavior of Mn doped BaCoO3

The structural, magnetic and electric properties of calcinated BaCo_1-xMn_xO₃ (x = 0.0-0.25) oxides are investigated by X-ray diffraction (XRD) and transmission electron microscopy, SQUID measurements, and conventional four-probe technique, respectively. XRD data show a 2H-type perovskite at x = 0.0, 10H-type crystal structure at x = 0.15, and mixed phases (2H- and 10H-types) at x = 0.05 and 0.10. The magnetisation-temperature curves reveal the antiferromagnetic phase of the 2H single phase and ferromagnetic behavior (brought by the observed hysteresis and remanent magnetization) at 5 K of the 10H-type structure. A transition from ferromagnetic to paramagnetic state is also observed with a transition temperature of around 47 K. Around this temperature region, specifically at 50 K, a semiconductor-insulator transition is found with a dielectric constant ε = 1.13. These results suggest that the 10H-type structure around the obtained transition temperature is a possible candidate for device applications of ferromagnetic oxides with dielectric properties.