Structural, magnetic and electrical transport properties of double perovskite Tb 2 MnCoO 6
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G. Ungar Department of Physics, Center for Optoelectronic Materials and Devices, Zhejiang Sci-Tech University, Hangzhou 310018, People’s Republic of China; and Department of Engineering Materials, University of Sheffield, Sheffield S1 3JD, South Yorkshire, United Kingdom
Y. Liu and J.Q. Shen Department of Physics, Center for Optoelectronic Materials and Devices, Zhejiang Sci-Tech University, Hangzhou 310018, People’s Republic of China
W.H. Tangb) State Key Laboratory of Information Photonics & Optical Communication, Beijing University of Posts and Telecommunications, Beijing 100876, People’s Republic of China (Received 11 December 2015; accepted 7 March 2016)
The double perovskite Tb2MnCoO6 and two simple perovskites TbMnO3 and TbCoO3 were synthesized by a solid sintering reaction method. The Rietveld refinement results based on the x-ray powder diffraction data identified all samples as orthorhombic perovskite structures with space group Pbnm (62). The lattice parameters of Tb2MnCoO6 were a 5 5.278 (3) Å, b 5 5.579 (4) Å, and c 5 7.513 (4) Å with a cell volume V 5 221.2 (6) Å3, Z 5 2. Meta-magnetic behavior was observed near 92 K for Tb2MnCoO6, which was considered to be related to the coexistence of and competition between the ferromagnetic order and antiferromagnetic order. Temperaturedependent resistance (R–T) was also measured. Compared with TbCoO3 and TbMnO3, Tb2MnCoO6 is more conductive, with its activation energy reduced from 0.3062 eV for TbCoO3 (0.2754 eV for TbMnO3) to 0.1949 eV. The results reported here can assist in understanding the multiferroic physics mechanism of double perovskite materials.
I. INTRODUCTION
The double perovskite structure with formula A2BB9O6, in which A is an alkali, alkaline earth, or rare earth element, consists of a cubic, corner-connected network of BO6 and B9O6 octahedra, where each BO6 octahedron is connected only to B9O6 octahedra. Compared to simple perovskites, this type of connection offers more possibilities for designing new magnetic materials due to the greater variety of magnetic exchange interactions. Recently, double perovskites have been found to show multiferroic behavior.1–3 These results encourage us to explore other double perovskites, which may offer us more chances to find applicable multiferroic materials or more deeply understand the mechanism involved. TbMnO3 is an orthorhombic perovskite manganite with a spiral magnetic structure at room temperature. There are differing views on the mechanism of coupling Contributing Editor: Michael E. McHenry Address all correspondence to these authors. a) e-mail: [email protected] b) e-mail: [email protected] DOI: 10.1557/jmr.2016.112 1038
J. Mater. Res., Vol. 31, No. 8, Apr 28, 2016
http://journals.cambridge.org
Downloaded: 28 Apr 2016
between ferromagnetic (FM) and ferroelectric in TbMnO3 at low temperature. Kimura et al. proposed that its ferroelectricity is induced by the deformation of the Mn–O–Mn bond.4 Other groups have proposed a mechanism based on electronic theory, considering the polarization charge to be
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