ENHANCED MAGNETIZATION IN BiFeO₃/BaTiO₃ MULTILAYERS: AN INTERFACE EFFECT?

Abstract

We have used pulsed laser deposition to grow BiFeO 3 /BaTiO 3 multilayers on SrTiO 3 substrates. The samples are characterized by Reflection High Energy Electron Diffraction (RHEED), Atomic Force Microscopy (AFM), and by X-ray diffraction measurements and modelling. The two multilayers investigated here have modulation periods A = 90Å and 180Å, while the total thickness of 1800Å is the same for both samples. Hence, twice as many interfaces are encountered for the A = 90Å than for the A = 180Å sample. SQUID magnetometer measurements performed on these multiferroic samples show that the magnetization is significantly larger for the smaller wavelength sample thus pointing to a multilayer effect between the magnetic susceptibility and the number of interfaces per unit volume.

Multiferroic BaTiO3–BiFeO3composite thin films and multilayers: strain engineering and magnetoelectric coupling

“…This tendency remains for the samples grown at 0.01 mbar but with about 50% smaller saturation magnetization (not shown here). This result is in good agreement with the observations made by (Toupet et al 2008). Toupet showed that the magnetization in BTO/BFO multilayers increases when the number of interfaces in the superlattice increases.…”

“…Only a few BFO-containing composites have been investigated up to now: (a) strain-mediated composite nanostructures BFO with CoFe 2 O 4 (Zavaliche et al 2005, Dix et al 2009, Aimon et al 2012, NiFe 2 O 4 (Zhan et al 2006) or Fe 3 O 4 (Weal et al 2010); (b) exchange-mediated multiferroics with electric field control of exchange bias in BFO with FeCo (Chu et al 2008), Ni 78 Fe 22 or (LaSr)MnO 3 (Wu et al 2010) and (c) combinations of BFO with another ferroelectric phase such as BTO: BFO/BTO multilayers showed an increased magnetization with double number of interfaces in structures with identical total thickness (Toupet et al 2008). Substitution of BFO by (NdBi)FeO 3 and BTO by BaSrTiO 3 in the multilayers results in even higher magnetization, up to 60 emu cm −3 (Ivanov et al 2012).…”

Enhanced ferroelectric photovoltaic response of BiFeO3/BaTiO3 multilayered structure

“…18,19 Some research groups have also studied BFO/BTO multilayered structures, but their photovoltaic properties are scarcely reported. 20,21 Toupet et al 22 and Yang et al…”

Effect of insertion of low leakage polar layer on leakage current and multiferroic properties of BiFeO3/BaTiO3 multilayer structure

“…It may be seen from the recent research that the properties may be enhanced by material engineering including doping with other metal ions or making multilayered structures [11][12][13][14][15][16][17]. Touplet et al and Yang et al reported an enhancement in magnetic properties by employing BiFeO 3 /BaTiO 3 multilayer system [18][19]. Lorenz et al showed that BaTiO 3 -BiFeO 3 multilayers show the highest magnetization of 2.3 emu cm −3 , due to interface magnetic moments and exchange coupling [12].…”

“…In the multilayered thin film structures, two different ferroic order materials allow modifications of the properties of parent materials by strain engineering [12]. BiFeO 3 /BaTiO 3 multilayers provide with a promising alternative in exploring the full potential of BiFeO 3 single layer thin film while maintaining the ferroelectric nature [18][19]. There have been few reports in recent years on improvement in multiferroic properties in multilayered thin film structures [12][13].…”