Multiferroic behaviour and the magneto-dielectric effect in Bi5FeTi3O15 thin films (original) (raw)
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Multiferroic properties of BiFeO3/BaTiO3 multilayered thin films
Physica B: Condensed Matter, 2014
Multilayered structures of multiferroic BiFeO 3 (BFO) and ferroelectric BaTiO 3 (BTO) have been fabricated using pulsed laser deposition (PLD). Ferromagnetic and ferroelectric properties of the multilayered system (BFO/BTO) have been investigated. It could be inferred that the magnetization increases with the incorporation of BTO buffer layer, which indicates a coupling between the ferroelectric and ferromagnetic orders. Vibrating sample magnetometer (VSM) measurements performed on the prepared multiferroic samples show that the magnetization is significantly increased (M s ¼ 56.88 emu/cm 3) for the multilayer system with more number of layers (four) keeping the total thickness of the multilayered system constant (350 nm) meanwhile maintaining the sufficiently enhanced ferroelectric properties (P r ¼29.68 mC/cm 2).
Electric and Magnetic Properties of Multiferroic BiFeO$_{3}$ and YMnO$_{3}$ Thin Films
IEEE Transactions on Magnetics, 2008
We grew rhombohedrally distorted BiFeO 3 and hexagonal YMnO 3 thin films on Pt/TiO 2 /SiO 2 /Si substrates via RF magnetron sputtering technique in a pure oxygen atmosphere. BiFeO 3 and YMnO 3 targets were self-made by the usual solid-state reaction method. We investigated the effects of deposition temperature upon crystalline structure, surface morphology, magnetization, and electrical polarization of BiFeO 3 and YMnO 3 thin films. The crystalline structure was studied by X-ray diffraction, and the topography of film surface was analyzed by atomic force microscopy. We also conducted measurements of ferroelectric and ferromagnetic hysteresis loops to study the electrical and magnetic behavior of the samples. Polarization, as a function of electric field in capacitor structures based on our BiFeO 3 films, shows hysteretic behavior with a coercive field of 54 kV/cm and a remanent polarization of 21 C/cm 2 ; whereas, YMnO 3 films show hysteretic behavior with coercive field of 2.4 kV/cm, remanent polarization of 1.2 C/cm 2 , and saturation polarization of 3.5 C/cm 2. Magnetization measurements of the BiFeO 3 films evidence weak ferromagnetism, that can be related to the presence of a small quantity of ferromagnetic impurities.
Journal of Applied Physics, 2012
Aurivillius phase Bi 5 Ti 3 Fe 0.7 Co 0.3 O 15 (BTF7C3O) thin films on a-quartz substrates were fabricated by a chemical solution deposition method and the room temperature ferroelectric and magnetic properties of this candidate multiferroic were compared with those of thin films of Mn 3þ substituted, Bi 5 Ti 3 Fe 0.7 Mn 0.3 O 15 (BTF7M3O). Vertical and lateral piezoresponse force microscopy (PFM) measurements of the films conclusively demonstrate that BTF7C3O and BTF7M3O thin films are piezoelectric and ferroelectric at room temperature, with the major polarization vector in the lateral plane of the films. No net magnetization was observed for the inplane superconducting quantum interference device (SQUID) magnetometry measurements of BTF7M3O thin films. In contrast, SQUID measurements of the BTF7C3O films clearly demonstrated ferromagnetic behavior, with a remanent magnetization, B r , of 6.37 emu/cm 3 (or 804 memu/g), remanent moment ¼ 4.99 Â 10 À5 emu. The BTF7C3O films were scrutinized by xray diffraction, high resolution transmission electron microscopy, scanning transmission electron microscopy, and energy dispersive x-ray analysis mapping to assess the prospect of the observed multiferroic properties being intrinsic to the main phase. The results of extensive micro-structural phase analysis demonstrated that the BTF7C3O films comprised of a 3.95% Fe/Co-rich spinel phase, likely CoFe 2 À x Ti x O 4 , which would account for the observed magnetic moment in the films. Additionally, x-ray magnetic circular dichroism photoemission electron microscopy (XMCD-PEEM) imaging confirmed that the majority of magnetic response arises from the Fe sites of Fe/Co-rich spinel phase inclusions. While the magnetic contribution from the main phase could not be determined by the XMCD-PEEM images, these data however imply that the Bi 5 Ti 3 Fe 0.7 Co 0.3 O 15 thin films are likely not single phase multiferroics at room temperature. The PFM results presented demonstrate that the naturally 2D nanostructured Bi 5 Ti 3 Fe 0.7 Co 0.3 O 15 phase is a novel ferroelectric and has potential commercial applications in high temperature piezoelectric and ferroelectric memory technologies. The implications for the conclusive demonstration of ferroelectric and ferromagnetic properties in single-phase materials of this type are discussed. V
Integrated Ferroelectrics, 2008
Experimental results on Bi2FeCrO6 (BFCO) epitaxial films deposited by laser ablation on SrTiO3 substrates are presented. It has been theoretically predicted using first-principles density functional theory that BFCO is ferrimagnetic (with a magnetic moment of 2muB per formula unit) and ferroelectric (with a polarization of ~80 microC/cm2 at 0K). The crystal structure investigated using X-ray diffraction shows that the films are epitaxial with a high degree of crystallinity. Chemical analysis carried out by X-ray Microanalysis and X-ray Photoelectron Spectroscopy indicates the correct cationic stoichiometry in the BFCO layer, namely (Bi:Fe:Cr = 2:1:1). Cross-section high-resolution transmission electron microscopy images together with selected area electron diffraction confirm the crystalline quality of the epitaxial BFCO films with no identifiable foreign phase or inclusion. The multiferroic character of BFCO is proven by piezoresponse force microscopy (PFM) and magnetic measurements showing that the films exhibit ferroelectric and magnetic hysteresis at room temperature. The local piezoelectric measurements show the presence of ferroelectric domains and their switching at the sub-micron scale.
Solid State Communications, 2010
Aurivillius-structured Bi4.15Nd0.85Ti3FeO15 multiferroic thin films with four perovskite slabs were deposited on Pt/Ti/ SiO2/Si substrates by the metal–organic decomposition method. The structural, dielectric and multiferroic properties of the films were investigated. Good ferroelectric behavior along with large dielectric constant and small loss factor were observed at room temperature. A weak ferromagnetic rather than an antiferromagnetic property was observed at room temperature by magnetic measurement. Moreover, the ferromagnetic property was enhanced when the temperature was below 13 K and a large saturation magnetization of about 5.4 emu/cm3 was obtained at 4 K. Possible reasons are put forward to discuss the complicated magnetic property.
Epitaxial Bi2FeCrO6 multiferroic thin films
Philosophical Magazine Letters, 2007
We present here experimental results obtained on Bi2FeCrO6 (BFCO) epitaxial films deposited by laser ablation directly on SrTiO3 substrates. It has been theoretically predicted, by Baettig and Spaldin, using first-principles density functional theory that BFCO is ferrimagnetic (with a magnetic moment of 2 Bohr magneton per formula unit) and ferroelectric (with a polarization of ~80 microC/cm2 at 0K). The crystal structure has been investigated using X-ray diffraction which shows that the films are epitaxial with a high crystallinity and have a degree of orientation depending of the deposition conditions and that is determined by the substrate crystal structure. Chemical analysis carried out by X-ray Microanalysis and X-ray Photoelectron Spectroscopy (XPS) indicates the correct cationic stoichiometry in the BFCO layer, namely (Bi:Fe:Cr = 2:1:1). XPS depth profiling revealed that the oxidation state of Fe and Cr ions in the film remains 3+ throughout the film thickness and that both Fe and Cr ions are homogeneously distributed throughout the depth. Cross-section high-resolution transmission electron microscopy images together with selected area electron diffraction confirm the crystalline quality of the epitaxial BFCO films with no identifiable foreign phase or inclusion. The multiferroic character of BFCO is proven by ferroelectric and magnetic measurements showing that the films exhibit ferroelectric and magnetic hysteresis at room temperature. In addition, local piezoelectric measurements carried out using piezoresponse force microscopy (PFM) show the presence of ferroelectric domains and their switching at the sub-micron scale.
Orientational dependence of multiferroic behaviors of La and Mn modified BiFeO3 thin films
2011 International Symposium on Applications of Ferroelectrics (ISAF/PFM) and 2011 International Symposium on Piezoresponse Force Microscopy and Nanoscale Phenomena in Polar Materials, 2011
Orientation engineered (La, Mn) co-substituted BiFe03 [BFOLMI thin films were deposited on CaRu03 buffered (LaAI03)O.3(Sr 2 AITa06)O.35 (LSATI (0011, (110J and (111J single crystal substrates, respectively, by pulsed laser deposition.
Multiferroic BiFeO3/BaTiO3 thin films fabricated by chemical solution deposition technique
MRS Proceedings, 2015
ABSTRACTThe BiFeO3/BaTiO3(BFO/BTO) multilayers were deposited on Pt/Ti/SiO2/Si substrates using sol-gel spin coating technique. The electric and magnetic studies on BFO/BTO multilayer structures were carried out for different number of layers. Enhancement in multiferroic properties were seen for all the prepared multilayers as compared to individual BTO and BFO thin films. Maximum value of ferroelectric polarization 71.18 µC/cm2and saturation magnetization 69.85 emu/cm3was obtained for multilayer structure having five layers. The observed enhancement in the multiferroic properties of the multilayer system is due to the increased interfacial stress and multiferroic coupling between the alternating layers.