Exploring the Magnetoelectric Coupling at the Composite Interfaces of FE/FM/FE Heterostructures

Abstract

Multiferroic materials have attracted considerable attention as possible candidates for a wide variety of future microelectronic and memory devices, although robust magnetoelectric (ME) coupling between electric and magnetic orders at room temperature still remains difficult to achieve. In order to obtain robust ME coupling at room temperature, we studied the Pb(Fe0.5Nb0.5)O3/Ni0.65Zn0.35Fe2O4/Pb(Fe0.5Nb0.5)O3 (PFN/NZFO/PFN) trilayer structure as a representative FE/FM/FE system. We report the ferroelectric, magnetic and ME properties of PFN/NZFO/PFN trilayer nanoscale heterostructure having dimensions 70/20/70 nm, at room temperature. The presence of only (00l) reflection of PFN and NZFO in the X-ray diffraction (XRD) patterns and electron diffraction patterns in Transmission Electron Microscopy (TEM) confirm the epitaxial growth of multilayer heterostructure. The distribution of the ferroelectric loop area in a wide area has been studied, suggesting that spatial variability of ferroelectric switching behavior is low, and film growth is of high quality. The ferroelectric and magnetic phase transitions of these heterostructures have been found at ~575 K and ~650 K, respectively which are well above room temperature. These nanostructures exhibit low loss tangent, large saturation polarization (Ps ~ 38 µC/cm2) and magnetization (Ms ~ 48 emu/cm3) with strong ME coupling at room temperature revealing them as potential candidates for nanoscale multifunctional and spintronics device applications.

Unravelling the nature of magneto-electric coupling in room temperature multiferroic particulate (PbFe0.5Nb0.5O3)–(Co0.6Zn0.4Fe1.7Mn0.3O4) composites

“…The key parameters such as dielectric constant, piezoelectric constant, mechanical quality factor, magnetostrictive coefficient, Curie, and Neel temperature should be examined properly before the selection of the individual phases for the composite formation 8 . PbFe 0.5 Nb 0.5 O 3 (PFN) is a single-phase multiferroics compound with high dielectric constant (3000 at 1 kHz), low dielectric loss (tanδ = 0.01 at 1 kHz), high piezoelectric coefficient (d 33 = 145 pC/N), good FE behaviour, weak magnetic properties with the existence of ME effect at low temperature 19 . It undergoes a ferroelectric-paraelectric transition (T C ) around 383 K, antiferromagnetic-paramagnetic transition (T N ) around 122–145 K, and a weak FM below 10 K 19 .…”

“…PbFe 0.5 Nb 0.5 O 3 (PFN) is a single-phase multiferroics compound with high dielectric constant (3000 at 1 kHz), low dielectric loss (tanδ = 0.01 at 1 kHz), high piezoelectric coefficient (d 33 = 145 pC/N), good FE behaviour, weak magnetic properties with the existence of ME effect at low temperature 19 . It undergoes a ferroelectric-paraelectric transition (T C ) around 383 K, antiferromagnetic-paramagnetic transition (T N ) around 122–145 K, and a weak FM below 10 K 19 . PFN also shows weak ferromagnetic behaviour around 300 K or above due to spin clustering and canted antiferromagnetic ordering of spins 20 .…”

Magnetoelectric Composites: Applications, Coupling Mechanisms, and Future Directions

“…The ME effect in composite systems is a product property, which arises because of the cross coupling between the electrical and magnetic order parameters of the FE and magnetic phases [ 64 ]. The separate ferroelectric and magnetic phase do not show a ME effect, but the hybrid composite system consisting of both the phases exhibits large ME coupling [ 65 ]. There are generally two types of ME coupling: (a) direct ME coupling and (b) converse ME coupling, depending on the elastic interactions and applied electric or magnetic field [ 32 , 46 ].…”

“…Epitaxial strain generated because of lattice mismatched growth is a nondestructive approach for significantly enhancing the functionalities [ 68 ]. The strain generated at multiple interfaces of multilayer oxide heterostructures and superlattices can give rise to new quantum states and enhanced physical functionalities [ 65 , 68 ]. Because strain plays an important role in determining ME coupling in composite structures, FE materials having high electro-strictive/piezoelectric coefficients and magnetic candidates having high piezomagnetism/magnetostriction along with high resistivities are necessary for designing different composite architectures to produce large ME coupling [ 12 , 32 , 50 ].…”

“…The ME coupling in composites are substantially reduced by defects, residual strains, grain boundaries, clamping effects, dislocations, and voids/pores [ 11 , 17 ]. Good strain transmission between the FE and magnetic phase is necessary in order to observe large ME coupling in composite structures [ 32 , 65 ]. However, well controlled strain generation and transmission in the composite structures is not trivial to obtain.…”