Magnetic and dielectric properties of metamagnetic Tb[Co.sub.0.5][Mn.sub.0.5][O.sub.3.07] ceramics

• Published in: Journal of materials science 2014-05, Vol.49 (10), p.3681
• Main Authors: Su, J, Zhang, J.T, Lu, X.M, Lu, C.J, He, J, Li, Q.C, Zhou, J, Zhu, J.S
• Format: Article
• Language: English
• Subjects: Anisotropy; Ceramic materials; Ceramics; Crystals; Dielectrics; Electrical conductivity; Ferromagnetism; Magnetic fields; Magnetization; Perovskite; Structure
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1007/s10853-014-8076-8

The ceramic Tb[Co.sub.0.5][Mn.sub.0.5][O.sub.3.07] of double-perovskite structure was prepared by solid-state reaction. Its crystal structure and magnetic and dielectric properties were investigated by first-principles calculations and experimental observations. Tb[Co.sub.0.5][Mn.sub.0.5][O.sub.3.07] possesses a monoclinic structure with [P2.sub.1]/n space group. The c axis is the easy-magnetization axis, and it is largely caused by [Co.sup.2+] anisotropy. The predominant valence states are [Mn.sup.4+] and [Co.sup.2+], with a small amount of Co3? coexisting with [Co.sup.2+]. The ordering of [Mn.sup.4+] and [Co.sup.2+] results in ferromagnetic [Mn.sup.4+]-[Co.sup.2+] interactions. Partial disorder of the B-site creates antiferromagnetic [Co.sup.2+]-O-[Co.sup.2+] or [Mn.sup.4+]O-[Mn.sup.4+] interactions. The origin of metamagnetism is associated with the coexistence of antiferromagnetic and ferromagnetic phases. The magnetic exchange bias is strongly dependent on magnetic field, which is considered to be related to the metamagnetic behavior. The possibility of spin glass behavior is excluded by AC susceptibility measurements. The two observed dielectric relaxations are caused by electrons hopping between [Co.sup.2+] and [Mn.sup.4+] and between [Co.sup.3+] and [Mn.sup.4+].