Eur. Phys. J. B (2013) 86: 504
https://doi.org/10.1140/epjb/e2013-40716-8

Regular Article

Critical thickness for ferroelectricity and magnetoelectric effect in multiferroic tunnel junction with symmetrical and asymmetrical electrodes

¹ School of Physics and Microelectronics science, Hunan University, Changsha 410082, Hunan, P.R. China
² College of Science, China Jiliang University, Hangzhou, Zhejiang 310083, P.R. China
³ Jiangsu Laboratory of Advanced Functional Materials, Department of Physics, Changshu Institute of Technology, Changshu 215500, Jiangshu, P.R. China

^a e-mail: mqcai@hnu.edu.cn

Received: 29 July 2013
Received in final form: 27 September 2013
Published online: 11 December 2013

Abstract

The critical thickness for ferroelectricity and magnetoelectric effects have been investigated for the multiferroic tunnel junction with symmetric and asymmetric metallic electrodes based on density functional theory. The ferroelectric polarization of a barrier is still retained down to 2 unit cells scale for the asymmetric multiferroic tunnel junction. The greater cause, leading to the reduction, or even complete elimination for the critical thickness, is the difference in the work function for the two asymmetrical electrodes. In addition, the effect of magnetoelectric coupling is obvious. The asymmetric multiferroic tunnel junction provides the possibility for the miniaturising and multifunctional spin electronic devices.