Room temperature multiferroicity and magnetoelectric coupling in Ca/Mn-modified BaTiO3

Abstract

Materials with magnetoelectric coupling (MEC) between ferroic orders at room temperature are an emerging field in modern technology and physics. BaTiO3 is a robust ferroelectric material in which several types of doping have led to MEC. Ca- and Mn-modified BaTiO3 has been studied with a series of Ba(1−x)Ca(x)Ti(1−y)Mn(y)O3 (x = y = 0, 0.03, 0.06, and 0.09) substitutions

here, MEC was only observed when x = 0.03. A mixed phase of tetragonal P4mm and hexagonal P63/mmc space groups of BaTiO3 are observed in the substituted samples, with nominal contribution of the hexagonal phase when x = 0.03. Substitution in BaTiO3 as described above results in structural modifications with reduced Ti-O-Ti bond angles and a large number of defects in the tetragonal phase, leading to weak ferromagnetism. Valence state study using XPS and XANES reveals an enhanced proportion of Mn3+ ions in the sample, which supports pseudo Jahn-Teller distortion, thereby supporting ferroelectricity and inducing weak magnetic ordering due to short range magnetic exchange interactions and bound magnetic polarons in the tetragonal phase at x = 0.03. The simultaneous existence of ferroelectricity and ferromagnetism in the tetragonal phase induces magnetoelectric coupling in this material. Furthermore, the linear response of polarization with an applied AC magnetic field indicates direct MEC. A magnetoelectric coupling coefficient (αME) of ∼0.704 mV cm−1 Oe−1 was obtained for a DC magnetic field of 800 Oe and an AC field of 40 Oe. This MEC was not observed for Ca and Mn substitutions in BaTiO3 at x = 0.06 or 0.09, which emphasizes the sensitivity of structural properties towards substitution. © 2025 The Royal Society of Chemistry.