Substrate clamping effect onto magnetoelectric coupling in multiferroic BaTiO₃-CoFe₂O₄ core-shell nanofibers via coaxial electrospinning

MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, School of Science, and Multi-disciplinary Materials Research Center, Frontier Institute of Science and Technology, and State Key Laboratory for Manufacturing System Engineering, Xi'an Jiaotong University 710049, Xi'an, PRC

^(a) fubi@mail.xjtu.edu.cn
^(b) yaodongyang@mail.xjtu.edu.cn
^(c) ypwang@mail.xjtu.edu.cn

Received: 20 September 2015
Accepted: 16 October 2015

Abstract

We report large lateral magnetoelectric (ME) coupling coefficients α₃₁ of and in substrate bonded and free-standing multiferroic BaTiO₃-CoFe₂O₄ (BTO-CFO) core-shell nanofibers (NFs) with and without substrate clamping effect, respectively. The BTO-CFO core-shell NFs were synthesised by a sol-gel coaxial electrospinning technique, and their ME coupling was directly observed by demonstrating the evolution of piezoelectric coefficient (d₃₃), ferroelectric domain, and phase contrast induced by an external magnetic field. These impressed α₃₁ coefficients originated from the nanoconfinement of the interphase elastic interaction between the ferromagnetic core fiber and the ferroelectric shell interlayer, as well as the strain transformation at the one-dimensional (1D) fiber boundary. This means that the decreasing substrate clamping effect results in an enhanced ME coupling in multiferroic NFs, which is similar to that of thin films. These findings make people understand the substrate clamping effect and enable nanoscale ME device applications.