Enhanced magnetoelectric coupling in dysprosium-doped BiFeO 3 on the formation of nanocomposite with SrFe 12 O 19 Anusree Das a , Nilesh Khamaru a , Sudipta Bandyopadhyay b , Souvik Chatterjee a , Dipankar Das a, * a UGC-DAE Consortium for Scientific Research, Kolkata Centre, III/LB-8, Bidhannagar, Kolkata, 700106, India b Department of Physics, University of Calcutta, Kolkata, 700009, India article info Article history: Received 22 September 2020 Received in revised form 2 November 2020 Accepted 3 November 2020 Available online xxx Keywords: Ferrite Nanocomposites Multiferroics Magnetic properties Dielectric properties abstract Nanocomposites (NCs) containing strontium hexaferrite (SrFe 12 O 19 , SFO) and dysprosium-substituted bismuth ferrite (Bi 0.9 Dy 0.1 FeO 3 , BDFO) with composition x SrFe 12 O 19 - (1-x) Bi 0.9 Dy 0.1 FeO 3 , with x ¼ 0.1, 0.2, and 0.3, have been synthesized using the sol-gel route and their structural, magnetic, dielectric and magnetoelectric properties have been investigated. Formation of pure crystalline x SFO - (1-x) BDFO NCs is confirmed by XRD measurements. Magnetization and dielectric constant (ε r ) of the pristine BiFeO 3 (BFO) have been found to increase on Dy-substitution. In the nanocomposite samples, magnetization increases, but dielectric constant decreases with increasing SFO content. Variation of capacitance of the NC samples in the presence of magnetic field up to 150 kOe indicates a substantial enhancement of the magnetoelectric (ME) coupling coefficient of BFO in the nanocomposites. ME coupling tends to improve with higher SFO content in the NCs. © 2020 Published by Elsevier B.V. 1. Introduction Materials with multifunctional properties have attracted immense attention of a vast community of scientists recently, because of their potential applications in various fields of physics and technology. Multiferroics are materials having two or more ferroic properties like ferro-/ferri-/antiferro-magnetism, ferroelec- tricity, and ferroelasticity. Some of them have an additional attractive feature of getting their magnetization tuned in the presence of an electric field, and modification of their electrical properties under the application of a magnetic field. This phe- nomenon is known as magnetoelectric (ME) effect [1]. Bismuth ferrite (BiFeO 3 ) is one of the most well-known and vastly studied multiferroics due to its room-temperature multiferroic properties and hence having potential for practical applications. It has quite high ferroelectric (FE) Curie transition temperature (~1103 K) and antiferromagnetic (AFM) N eel temperature (~643 K), that enable this compound to be a room temperature multiferroic [2]. But a few drawbacks hinder the possibility of using this compound for device applications. It has a negligible magnetic moment due to being a G- type antiferromagnet with spiral spin ordering. It exhibits high leakage current and low resistivity causing difficulty in achieving a saturated ferroelectric loop. Besides that, due to a significant dif- ference between the AFM and FE transition temperatures, BiFeO 3 (BFO) shows weak magnetoelectric coupling, and hence, it has a very low ME coefficient. Several strategies have been adopted to modify magnetic, ferroelectric, and magnetoelectric properties of BFO such as, substitution of the proper elements in Bi 3þ and/or Fe 3þ sites or making a composite comprising BFO and other suitable compounds [3e9]. Our previous studies on nanocomposites comprising BFO and a hard ferrite (SrFe 12 O 19 ), as well as a relatively softer ferrite (CoFe 2 O 4 ), showed that in both the cases, magnetic and magnetoelectric properties of BFO got enhanced after forma- tion of the nanocomposites [10, 11]. However, dielectric properties of BFO were found to get deteriorated on the formation of the said NCs. The present study has been taken up to overcome this short- coming by anticipating an enhancement of dielectric properties of BFO on substitution of a suitable rare-earth element prior to the formation of the nanocomposite with a hard ferrite. Since the magnetoelectric coupling coefficient of a sample depends on dielectric constant as well as the magnetic moment of the sample [11], higher dielectric constant after rare-earth substitution is ex- pected to enhance further the ME coupling coefficient of the pre- sent NCs. Improvement in ferroelectric, magnetic, and * Corresponding author. E-mail address: ddas@alpha.iuc.res.in (D. Das). Contents lists available at ScienceDirect Journal of Alloys and Compounds journal homepage: http://www.elsevier.com/locate/jalcom https://doi.org/10.1016/j.jallcom.2020.157821 0925-8388/© 2020 Published by Elsevier B.V. Journal of Alloys and Compounds xxx (xxxx) xxx Please cite this article as: A. Das, N. Khamaru, S. Bandyopadhyay et al., Enhanced magnetoelectric coupling in dysprosium-doped BiFeO 3 on the formation of nanocomposite with SrFe 12 O 19 , Journal of Alloys and Compounds, https://doi.org/10.1016/j.jallcom.2020.157821