© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.pss-rapid.com pss Phys. Status Solidi RRL 6, No. 6, 244–246 (2012) / DOI 10.1002/pssr.201206135 Nanoscale magnetoelectric coupling in multiferroic BiFeO 3 nanowires K. Prashanthi *, 1 , P. M. Shaibani 1 , A. Sohrabi 1 , T. S. Natarajan 2 , and T. Thundat 1 1 Dept. of Chemical and Materials Engineering, University of Alberta, Edmonton, Alberta, Canada 2 Dept. of Physics, Indian Institute of Technology Madras, Chennai, India Received 29 March 2012, revised 25 April 2012, accepted 25 April 2012 Published online 27 April 2012 Keywords BiFeO 3 , magnetic force microscopy, MFM, multiferroics, magnetoelectric effects * Corresponding author: e-mail kovur@ualberta.ca, Phone: +1780 492 8664, Fax: +1780 492 2881 © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 1 Introduction Bismuth ferrite (BiFeO 3 , BFO) is one of the very few room temperature multiferroic materi- als with a simultaneous coexistence of ferroelectric (T C = 810 °C) and antiferromagnetic order (T N = 380 °C) parameters. It is also reported that even though BFO has an antiferromagnetic spin ordering, it displays a weak mag- netic moment arising from a canted spin structure [1, 2]. Extensive work has been reported on growth and charac- terization of BFO thin films due to their immense applica- tion potential in spintronics [3], non-volatile memories [4], microelectromechanical systems (MEMS) [5], and switchable photovoltaics [6]. However, one-dimensional (1D) nanostructures, such as nanowires [7, 8], nanotubes [9] and nanofibers [10, 11] are expected to show excellent properties compared to the conventional structures due to the large surface area [12] and quantum size effects [13]. Several efforts therefore, have been directed towards fabri- cating BFO nanostructures using the template technique [9], hydrothermal synthesis [14], sol–gel combustion method [15], soft chemical methods [16], and electrospin- ning technique [10, 11]. Controlling magnetism with an external electric field and electric polarization by an exter- nal magnetic field in nanostructured BFO is one of the most important attempts in order to realize nanoscale de- vices with unique functionalities utilizing the coupling be- tween two parameters. Though there are several literature reports on magnetoelectric (ME) coupling of pure and modified BFO bulk and thin films [17–19], however, to the best of our knowledge, there are no literature reports on lo- cal ME coupling of nanostructured BFO. In this Letter, we report on the local probing of ME coupling in BFO NWs prepared by sol–gel based electrospinning technique. Us- ing magnetic force microscopy, the evolution of a mag- netic domain pattern with application of external electric field has been observed confirming the ME coupling in BFO NWs. 2 Experimentation The BFO sol–gel precursor solu- tion was prepared by dissolving Bi(NO 3 ) 3 ⋅ 5H 2 O and Fe(NO 3 ) 3 ⋅ 9H 2 O salts in stoichiometric proportions in 2-methoxyethanol. The pH value of the solution was ad- justed to 4 by adding ethanolamine. This mixture was magnetically stirred for 2 hours at room temperature. The polymer solution of 15 wt% was prepared by dissolving nylon-6 crystals to formic acid. The prepared BFO solution was added to this polymer solution drop by drop to obtain Nanoscale magnetoelectric (ME) coupling has been observed in multiferroic BiFeO 3 (BFO) nanowires (NWs) synthesized by sol–gel based electrospinning technique. Under externally imposed electric fields these NWs exhibit the systematic evo- lution of a magnetic domain pattern as established by mag- netic force microscopy (MFM), confirming the presence of ME coupling. Interestingly, the effect persists even after the electric field is removed, thereby implying an electric-field- induced magnetic hysteresis phenomenon in BFO NWs. The estimated ME coupling coefficient from tip–sample interac- tions is α 33 = 2.2 × 10 −10 sm −1 , and the equivalent ME voltage coefficient is 0.49 V cm –1 Oe −1 . The obtained values of the ME coupling coefficient are higher than the reported values for BFO bulk and thin films. These results promise one- dimensional (1D) multiferroic BFO NWs as potential candi- date for manipulating magnetism through electric field at the nanoscale and provide great opportunities towards magneto- electrically tunable multiferroic devices.