Room temperature multiferroicity and magnetodielectric coupling in 0–3 composite thin films

Abstract

Magnetoelectric (ME) composite thin films are promising candidates for novel applications in future nanoelectronics, spintronics, memory, and other multifunctional devices as they exhibit much higher ME coupling and transition temperatures (Tc) than well-known single phase multiferroics discovered to date. Among the three types of multiferroic composite nanostructures, (2–2) layered and (1–3) vertically aligned composite nanostructures exhibit comparatively smaller ME coupling due to different shortcomings that restrict their use in many applications. Here, we study the morphological, piezoresponse force microscopic (PFM), ferroelectric, magnetic, and magnetodielectric properties of 0–3 [magnetic nanoparticles (0) homogeneously distributed in ferroelectric matrices (3)] multiferroic composite thin films. The Pb(Fe0.5Nb0.5)O3 (PFN)–Ni0.65Zn0.35Fe2O4 (NZFO) particulate composite films were synthesized by pulsed laser deposition. These particulate composite thin films are completely c-axis oriented with very low surface roughness. We observed magnetic and ferroelectric Tc above room temperature (RT) for all composite thin films. The PFN–NZFO 0–3 composites exhibit large polarization, high saturated magnetization with low coercive field, and low dielectric loss along with magnetodielectric coupling at RT. These nanocomposites might be utilized in next generation nano/microelectronics and spintronic devices.

Magnetoelectric Composites: Applications, Coupling Mechanisms, and Future Directions

“…It should be noted that the piezoelectric effect is a linear change of polarization as a function of applied stress or change in strain as a function of E , whereas electrostriction is a quadradic change of strain with applied E [ 1 , 2 ]. This coupling is called direct ME coupling [ 17 , 32 ]. In this case, the coupling takes place via mechanical strain transmission (which is an elastic interaction) between the FE and magnetic phases [ 2 ].…”

“…Magnetoelectric (ME) coupling originates due to the coupling between FE and FM ordering parameters, where polarization ( P ) can be switched and/or tuned by a magnetic field ( H ) and magnetization ( M ) can be manipulated and/or switched via an electric field ( E ) [ 2 , 6 , 9 , 10 ]. ME-MF materials are rich in fundamental physics and they have great potential for applications in novel devices, such as ultra-low power and highly dense logic-memory, radio- and high-frequency, micro(nano) electronic, sensors, energy harvesting, actuators, spintronics, miniature antennas, terahertz emitters, electric-field controlled FM resonance, and other multifunctional devices [ 2 , 4 , 6 , 7 , 9 , 11 , 12 , 13 , 14 , 15 , 16 , 17 ]. The coexistence of electric polarization and magnetization in a single-phase makes them suitable for multistate memory devices, as P and M are used to encode binary information in FRAM (FE random-access memories) and MRAM (magnetic random-access memories), respectively [ 5 , 13 , 16 , 18 , 19 , 20 ].…”

“…The majority of the single-phase MF materials have a magnetic transition temperature ( T C ) below RT. Because of the large difference between the FE and magnetic T C , the ME coupling is observed to be very small [ 17 , 22 , 23 ]. For practical applications, MF materials should exhibit large polarization and magnetization, along with strong ME coupling at room temperature (RT) [ 3 , 4 , 5 , 9 , 19 ].…”

“…The possible composite architecture depending on the connectivity are: 0-0, 0-1, 1-1, 2-1, 3-1, 3-2, 3-3, 0-2, 1-2, 2-2, and some hybrid architectures, where the number implies the dimension of the magnetic and ferroelectric components, respectively [ 32 , 46 ]. The most commonly used ME architectures with successfully proven enhanced physical properties are: 0-3 particulate composites (where the magnetic nanoparticles (0-dimensional) are dispersed in ferroelectric matrices (three-dimensional)), 1-3 rod composites (where one-dimensional rods are grown in three-dimensional ferroelectric matrix), and 2-2 layered composites (where two-dimensional magnetic thick/thin layers are grown on two-dimensional ferroelectric thin films, and the periodicity might more than one) [ 17 , 32 , 46 , 47 , 48 , 49 ]. Figure 2 shows the 0-3, 1-3, and 2-2 composite nanostructures.…”

“…In order to observe large ME coupling, various types of composite systems have been synthesized, such as (a) FE-FM (antiferro/ferrimagnetic) composites, (b) MF-MF composites, (c) MF-FM (antiferro/ferrimagnetic) composites, and (d) FE-MF composites [ 15 , 17 ]. Most of the composite architectures have been designed in different connectivity utilizing Pb(Fe 0.5 Nb 0.5 )O 3 , BaTiO 3 , Ba 1−x Sr x TiO 3 , BiFeO 3 , Pb(Zr 1−x Ti x )O 3 , and PbTiO 3 as FE candidates and La 1−x Sr x MnO 3 , Fe 3 O 4 , CoFe 2 O 4, NiFe 2 O 4 , Ni 1−x Zn x Fe 2 O 4 , and Co 1−x Zn x Fe 2 O 4 as magnetic component [ 15 , 34 , 36 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 ].…”