Magnetic and structural properties of BiFeO3 thin films grown epitaxially on SrTiO3/Si substrates (original) (raw)
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Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 2013
We report the epitaxial growth of BiFeO3 by pulsed electron deposition and the resulting crystal quality, magnetic and nanoscale switching properties. X-ray diffraction shows high quality single phase, epitaxial (001) oriented films grown on SrTiO3 (001) substrates. Both field and temperature dependent magnetic properties reveal an antiferromagnetic behavior of the films.
Influence of parasitic phases on the properties of BiFeO[sub 3] epitaxial thin films
Applied Physics Letters, 2005
We have explored the influence of deposition pressure and temperature on the growth of BiFeO 3 thin films by pulsed laser deposition onto (001)-oriented SrTiO 3 substrates. Singlephase BiFeO 3 films are obtained in a region close to 10 -2 mbar and 580°C. In non-optimal conditions, X-ray diffraction reveals the presence of Fe oxides or of Bi 2 O 3 . We address the influence of these parasitic phases on the magnetic and electrical properties of the films and show that films with Fe 2 O 3 systematically exhibit a ferromagnetic behaviour, while singlephase films have a low bulk-like magnetic moment. Conductive-tip atomic force microscopy mappings also indicate that Bi 2 O 3 conductive outgrowths create shortcuts through the BiFeO 3 films, thus preventing their practical use as ferroelectric elements in functional heterostructures.
Synthesis and ferroelectric properties of epitaxial BiFeO3 thin films grown by sputtering
Applied Physics Letters, 2006
We have grown epitaxial BiFeO 3 thin films with smooth surfaces on ͑001͒, ͑101͒, and ͑111͒ SrTiO 3 substrates using sputtering. Four-circle x-ray diffraction and cross-sectional transmission electron microscopy show that the BiFeO 3 thin films have rhombohedral symmetry although small monoclinic distortions have not been ruled out. Stripe ferroelectric domains oriented perpendicular to the substrate miscut direction and free of impurity phase are observed in BiFeO 3 on high miscut ͑4°͒ ͑001͒ SrTiO 3 , which attributes to a relatively high value of remanent polarization ͑ϳ71 C/cm 2 ͒. Films grown on low miscut ͑0.8°͒ SrTiO 3 have a small amount of impure phase ␣-Fe 2 O 3 which contributes to lower the polarization values ͑ϳ63 C/cm 2 ͒. The BiFeO 3 films grown on ͑101͒ and ͑111͒ SrTiO 3 exhibited remanent polarizations of 86 and 98 C/cm 2 , respectively.
Role of oxygen in multiferroic behavior of BiFeO3 films grown on 0.2% Nb doped SrTiO3
Solid State Communications, 2013
Effect of oxygen partial pressure on the structural, transport and magnetic properties of BiFeO 3 (BFO) films grown on n-type conducting SrNb 0.002 Ti 0.998 O 3 (SNTO) substrates has been investigated. Variation in oxygen partial pressure, during pulsed laser deposition (PLD), results in the modifications in the physical properties of the films. Rutherford Backscattering (RBS) measurement shows that, BFO/SNTO films grown at 100 and 300 mT oxygen partial pressures, exhibit better polarization and magnetization. Tuning of electrical and magnetic properties with oxygen partial pressure has been discussed in the light of oxygen vacancies. Various charge transport mechanisms have been discussed to understand the leakage current mechanisms in BFO/SNTO films.
Adsorption-controlled molecular-beam epitaxial growth of BiFeO3
Applied Physics Letters, 2007
BiFeO 3 thin films have been deposited on ͑111͒ SrTiO 3 single crystal substrates by reactive molecular-beam epitaxy in an adsorption-controlled growth regime. This is achieved by supplying a bismuth overpressure and utilizing the differential vapor pressures between bismuth oxides and BiFeO 3 to control stoichiometry. Four-circle x-ray diffraction reveals phase-pure, untwinned, epitaxial, ͑0001͒-oriented films with rocking curve full width at half maximum values as narrow as 25 arc sec ͑0.007°͒. Second harmonic generation polar plots combined with diffraction establish the crystallographic point group of these untwinned epitaxial films to be 3m at room temperature.
Phase pure epitaxial growth of BiFeO 3 films: An effect of oxygen partial pressure
Solid State Communications, 2017
We report the growth of bismuth ferrite, BiFeO 3 (BFO), thin films by varying oxygen partial pressure (230, 100 and 10mTorr) in pulsed laser deposition system using 10% bismuth excess BFO target on SrTiO 3 (001) [STO] substrates at 700°C each for 15min duration. Xray diffraction shows the presence of an impurity phase along with BFO peaks for 230mTorr film, whereas oriented BFO film is observed for 100mTorr film with a small impurity phase. Importantly, epitaxial growth of BFO is observed without any impurity phase and with sufficiently increased strain for the 10mTorr film, confirmed by the reciprocal space mapping of (002) and (103) reflections. UV-Raman measurements have been performed on as grown films and the 10mTorr BFO film after annealing up to 500 o C to check its thermal stability. Atomic force microscopic (AFM) study reveals that the 10mTorr BFO film shows a lower roughness as compared to 100mTorr and 230mTorr films. Fast Fourier Transform (FFT) analysis in AFM shows a fourfold symmetric structure suggesting the presence of both modes of pattern-orientation in 230mTorr BFO film whereas an elongated bright spot along the y-direction in the FFT of 10mTorr BFO film suggests the growth tendency to be along the y-direction.
Tuning the atomic and domain structure of epitaxial films of multiferroic BiFeO_{3}
Physical Review B, 2010
Recent works have shown that the domain walls of room-temperature multiferroic BiFeO3 (BFO) thin films can display distinct and promising functionalities. It is thus important to understand the mechanisms underlying domain formation in these films. High-resolution x-ray diffraction and piezo-force microscopy, combined with first-principles simulations, have allowed us to characterize both the atomic and domain structure of BFO films grown under compressive strain on (001)-SrTiO3, as a function of thickness. We derive a twining model that describes the experimental observations and explains why the 71 • domain walls are the ones commonly observed in these films. This understanding provides us with a new degree of freedom to control the structure and, thus, the properties of BiFeO3 thin films.
Epitaxial growth of BiFeO3 thin films by LPE and sol–gel methods
Journal of Magnetism and Magnetic Materials, 2004
Epitaxial BiFeO 3 thin films have been grown on the (0 0 1) SrTiO 3 and LaAlO 3 substrates by liquid phase epitaxy (LPE) and sol-gel methods. The films had an in-plane texture of 21 and out-plane texture of 0.61 and showed a 4-fold symmetry about the c-axis, indicating a distortion of the bulk rhombohedral cell to a tetragonal or cubic structure. The LPE films were both ferroelectric and ferromagnetic. The sol-gel films showed a small linear increase of the magnetisation with the applied magnetic field, indicating they possibly had the same antiferromagnetic behaviour as the bulk crystal. The LPE films exhibited a large leakage current, which probably originated from a relatively high level of Fe 2+ in the films induced by the high growth temperature. Fe 2+ might also account for the origin of the ferromagnetism in LPE films.
Applied Physics Letters, 2012
The growth mechanism of a BiFeO 3 layer deposited on self assembled (0.65) BiFeO 3-(0.35) CoFe 2 O 4 (BFO-CFO) composite thin films was studied. Epitaxial and self-assembled BFO-CFO thin films were deposited on SrTiO 3 (111) substrates by pulsed laser deposition and were subsequently used as a seed layer for the deposition of an additional BFO layer. x-ray line scans showed the heterostructures were highly epitaxial. Cross-sectional scanning electron microscopy and focused ion beam images revealed the top BFO layer grew preferentially from BFO nanopillars in the BFO-CFO thin films, thus, demonstrating controlled growth. The multiferroic properties of this new nanostructure were then studied. V