Room temperature Multiferroicity and Magnetoelectric coupling in Ca/Mn modified BaTiO3

TL;DR

This study demonstrates room temperature multiferroicity and magnetoelectric coupling in Ca/Mn modified BaTiO3, with optimal properties at specific doping levels due to structural and valence state changes.

Contribution

It provides the first detailed analysis of Ca/Mn doping effects on multiferroicity and MEC in BaTiO3, highlighting the role of structural phases and Mn valence states.

Findings

MEC observed only at x=0.03 doping level.

Magnetoelectric coefficient ~44 mVcm-1Oe-1 at room temperature.

Structural phase mixture influences ferroelectric and magnetic properties.

Abstract

Materials with magnetoelectric coupling (MEC) between ferroic orders at room temperature are emerging field in modern technology and physics. BaTiO3 is a robust ferroelectric in which several doping has led to MEC. In Ca and Mn modified BaTiO3 has been study with a series of Ba(1-x)Ca(x)Ti(1-y)Mn(y)O3 (x=y= 0, 0.03, 0.06, 0.09), in this MEC was only observed in x=0.03. The structural modifications with changing substitution reveal a reduced Ti-O-Ti bond angle for this sample which is the most ferromagnetic in nature. A mixed phase of tetragonal P4mm and hexagonal P63/mmc space groups of BaTiO3 is observed in the substituted samples, with nominal contribution of the hexagonal phase for x=0.03. A valence state study using XPS and XANES reveals the presence of enhanced proportion of Mn3+ ions in the sample which support a pseudo Jahn-Teller distortion, thereby supporting the ferroelectricity for x=0.03. Direct evidences of MEC was obtained from magnetoelectric measurements. A magnetoelectric coupling coefficient, {\alpha}ME ~44 mVcm-1Oe-1 was obtained for dc magnetic field of 600 Oe and a 10Hz ac field of 40 Oe. Such MEC was not observed for higher substitution which emphasizes the sensitivity of the structural properties on substitution.