Hybrid Multiferroic Nanostructure with Magnetic–Dielectric Coupling

Abstract

The development of methods to economically synthesize single wire structured multiferroic systems with room temperature spin−charge coupling is expected to be important for building next-generation multifunctional devices with ultralow power consumption. We demonstrate the fabrication of a single nanowire multiferroic system, a new geometry, exhibiting room temperature magnetodielectric coupling. A coaxial nanotube/nanowire heterostructure of barium titanate (BaTiO 3 , BTO) and cobalt (Co) has been synthesized using a template-assisted method. Room temperature ferromagnetism and ferroelectricity were exhibited by this coaxial system, indicating the coexistence of more than one ferroic interaction in this composite system. KEYWORDS: Multiferroic materials, 1D heterostructure, barium titanate nanotubes, Co nanowires, spin−charge coupling, magnetocapacitance O ne-dimensional (1D) nanostructures such as nanotubes and nanowires attract considerable scientific attention because of their novel structure and physical properties, which can differ significantly from their bulk or thin film counter analogues. 1−3 From a practical standpoint, nanowires and nanotubes are the focus of intensive research effort owing to their unique applications in the fabrication of nanoscale devices and interconnects. 4 Multiferroic materials exhibit more than one ferroic order simultaneously, such as ferromagnetic/antiferromagnetic or ferroelectric/ferroelastic/ferrotoroidic. 5 However, the abundance of intrinsic multiferroic materials is sharply limited by the competing symmetry requirements for each type of ferroic order. Generally, ferroelectricity is associated with an empty outer shell d electrons (known as d 0 ness) while magnetic ordering requires unpaired d or f electrons, i.e., partially filled. 6 While these types of fundamental incompatibilities can make it challenging to identify intrinsic multiferroics, forming nanoscale composites of different ferroic materials to produce multiferroic superstructures provides an alternate method to introduce the desired materials properties. The coupling between the ferroic order parameters can be modulated by heteroepitaxial strain and crystal chemistry. 6,7 The development of magnetoelectric multiferroics, having coexisting magnetic and ferroelectric order, opens the possibility of controlling the magnetic/electric structure using either electric or magnetic fields. This type of cross-control requires a significant coupling between charge and spin or, in other words, a coupling between electric polarization and magnetic moment. This characteristic behavior is of considerable scientific and technological interest, and a number of studies are being conducted to design new multiferroic structures to foster a great understanding of the factors that promote the coupling between magnetic and ferroelectric order parameters. 6−18 Potential applications for multiferroic materials range from multiple-state data storage elements, to magnetically tunable high frequency electrical devices such ...

Lead free heterogeneous multilayers with giant magneto electric coupling for microelectronics/microelectromechanical systems applications

“…18 Also, charge redistribution induced by the interfacial boundaries of the ferroelectric layer may also induce changes in ferromagnetic ordering as per the polarization direction and thereby contributing to the giant magnetoelectric response. 27 The investigation directly points towards the possible applications in the microelectronics and MEMS industry. Magneto-electric cantilevers can be fabricated by partial dissolving of the silicon substrates (Scheme 2).…”

Magnetic and dielectric properties of Ni0.5Zn0.5Fe2O4/barium titanate (BaTiO3) ceramic composites prepared by an in situ sol–gel method

“…In recent years, lots of the researches have been explored and studied the intrinsic or extrinsic factors that influence the electromagnetic properties of these ferroelectric/ferromagnetic composites although the depth of understanding is still far from satisfaction [9]. However, natural multiferroic single-phase materials are very less, as the competing symmetry requirements for each kind of ferroic materials are different, for example, ferroelectricity needs d 0 in the outer electron configuration, while d shell electrons of ferromagnetic materials call for being partially filled [11,12]. Based on this limitation, many works turn to develop ferromagnetic-ferroelectric ceramic composite materials to meet the requirements of the multifunctional components [13][14][15].…”

Thickness-Dependent Magnetocapacitance of Ni0.98Co0.02Fe2O4/BaTiO3/Ni0.98Co0.02Fe2O4 Trilayers

“…14 Complex structures can be realized by making multilayer thin films composed of ferromagnetic and ferroelectric materials on a substrate. 15,16 To apply the ME effect directly in electrical systems, for a small device it is beneficial to use thin films rather than the bulk form. [17][18][19][20][21][22] We have fabricated a magnetocapacitor with a three-layer sandwich structure.…”