Local ferroelectric switching properties in BiFeO3 microstructures and their piezomagnetic response

2005 ◽  
Vol 902 ◽  
Author(s):  
Catalin Harnagea ◽  
Cristian Victor Cojocaru ◽  
Alain Pignolet

AbstractWe report here the successful fabrication of BiFeO3 (BFO) isolated micron-sized structures by pulsed laser deposition. The islands have a relatively constant aspect ratio (height/lateral size) of 0.1-0.3. We present their local ferroelectric characterization, using piezoresponse force microscopy (PFM), showing that the micron-sized BFO islands exhibit a strong piezoresponse and have ferroelectric domains with lateral sizes down to the 100 nm range. We also present here the first results of Magnetostriction Force Microscopy experiments performed on these structures. On ferromagnetic samples this method reveals a piezomagnetic or magnetostriction contrast, associated with magnetic domains. In our case, we show that the contrast can be associated to the magnetoelectric effect.

2012 ◽  
Vol 1477 ◽  
Author(s):  
C. I. Enriquez-Flores ◽  
J. J. Gervacio-Arciniega ◽  
F. J. Flores-Ruiz ◽  
D. Cardona ◽  
E. Camps ◽  
...  

ABSTRACTBismuth iron oxide BFO films were produced by the pulsed laser deposition technique. These films are a mixture of BiFeO3 ferroelectrical and Bi25FeO40 piezoelectrical phases. The ferroelectrical domain structure of these films was studied via contact resonance piezoresponse force microscopy (CR-PFM) and resonance tracking PFM (RT-PFM). The proportions of area of these BFO phases were derived from the PFM images. The ferroelectrical domain size corresponds to the size of the BiFeO3 crystals. The CR-PFM and RT-PFM techniques allowed us to be able to distinguish between the ferroelectric domains and the piezoelectric regions existing in the polycrystalline films.


2014 ◽  
Vol 1025-1026 ◽  
pp. 427-431
Author(s):  
Ping Gao ◽  
Wei Zhang ◽  
Wei Tian Wang

Orthorhombic HoMnO3 films were prepared epitaxially on Nb-doped SrTiO3 single crystal substrates by using pulsed laser deposition technique. The films showed perfectly a-axis crystallographic orientations. X-ray diffraction and atomic force microscopy were used to characterize the films. The complex dielectric properties were measured as functions of frequency (40 Hz~1 MHz) and temperature (80 K~300 K) with a signal amplitude of 50 mv. The respective dielectric relaxation peaks shifted to higher frequency as the measuring temperature increased, with the same development of real part of the complex permittivity. The cole-cole diagram was obtained according to the Debye model, and the effects of relaxation process were discussed.


1999 ◽  
Vol 574 ◽  
Author(s):  
V. Trtík ◽  
F. Sánchez ◽  
C. Ferrater ◽  
M. Varela ◽  
L. Fábrega ◽  
...  

AbstractYBa2Cu3Oy/SrTiO3/La2/3Sr1/3MnO3 heterostructures have been deposited on LaAlO3(001) and SrTiO3(001) substrates by pulsed laser deposition. First, the influence of deposition conditions on crystallinity and morphology of single LSMO films was examined. Results were used for preparation of heterostructures in tri-layer and cross-strip geometry. Cross-strip geometry was defined by direct shadow mask patterning. Different characterization techniques have been used to determine and correlate the heterostructure properties. A complete analysis of the crystal structure has been carried out with a four-circle difractometer. Morphology has been studied by scanning electron microscopy and atomic force microscopy in order to determine surface roughness and droplet density. Basic electrical properties of films have been determined.


Author(s):  
Sudheer Neralla ◽  
Sergey Yarmolenko ◽  
Dhananjay Kumar ◽  
Devdas Pai ◽  
Jag Sankar

Alumina is a widely used ceramic material due to its high hardness, wear resistance and dielectric properties. The study of phase transformation and its correlation to the mechanical properties of alumina is essential. In this study, interfacial adhesion properties of alumina thin films are studied using cross-sectional nanoindentation (CSN) technique. Alumina thin films are deposited at 200 and 700 °C, on Si (100) substrates with a weak Silica interface, using pulsed laser deposition (PLD) process. Effect of annealing on the surface morphology of the thin films is studied using atomic force microscopy. Xray diffraction studies revealed that alumina thin films are amorphous in nature at 200 °C and polycrystalline with predominant gamma alumina phase at 700 °C.


Materials ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1327 ◽  
Author(s):  
Ursic ◽  
Bencan ◽  
Prah ◽  
Dragomir ◽  
Malic

A complex domain structure with variations in the morphology is observed at ambient temperature in monoclinic Pb(Fe1/2Nb1/2)O3. Using electron microscopy and piezoresponse force microscopy, it is possible to reveal micrometre-sized wedge, lamellar-like, and irregularly shaped domains. By increasing the temperature, the domain structure persists up to 80 °C, and then starts to disappear at around 100 °C due to the proximity of the ferroelectric–paraelectric phase transition, in agreement with macroscopic dielectric measurements. In order to understand to what degree domain switching can occur in the ceramic, the mobility of the domain walls was studied at ambient temperature. The in situ poling experiment performed using piezoresponse force microscopy resulted in an almost perfectly poled area, providing evidence that all types of domains can be easily switched. By poling half an area with 20 V and the other half with −20 V, two domains separated by a straight domain wall were created, indicating that Pb(Fe1/2Nb1/2)O3 is a promising material for domain-wall engineering.


2008 ◽  
Vol 8 (11) ◽  
pp. 5748-5752
Author(s):  
S. Krishnamurthy ◽  
T. Donnelly ◽  
N. McEvoy ◽  
W. Blau ◽  
J. G. Lunney ◽  
...  

We report the growth of carbon nanotubes on the size controlled iron catalytic nanoparticles. The nanotubes were grown by thermal chemical vapour deposition (CVD) in the temperature range 600–850 °C. The Fe films were deposited on silicon by pulsed laser deposition in vacuum. Atomic force microscopy measurements were performed on the catalytic nanoparticles. The topography of the catalytic nanoparticles shows the homogenous distribution of Fe catalyst. We observe the nanotubes are produced only at temperatures between 650 and 800 °C, and within this narrow temperature regime the yield of nanotubes reaches a maximum around 750 °C and then declines. Raman measurements illustrate a high G/D peak ratio indicating good nanotube quality. By further defining the size of the catalyst the diameter of these carbon nanotubes can be controlled.


2012 ◽  
Vol 1432 ◽  
Author(s):  
M. Baseer Haider ◽  
M. F. Al-Kuhaili ◽  
S. M. A. Durrani ◽  
Imran Bakhtiari

Abstract:Gallium nitride thin films were grown by pulsed laser deposition. Subsequently, post-growth annealing of the samples was performed at 400, and 600 oC in the nitrogen atmosphere. Surface morphology of the as-grown and annealed samples was performed by atomic force microscopy, surface roughness of the films improved after annealing. Chemical analysis of the samples was performed using x-ray photon spectroscopy, stoichiometric Gallium nitride thin films were obtained for the samples annealed at 600 oC. Optical measurements of the samples were performed to investigate the effect of annealing on the band gap and optical constants the films.


2000 ◽  
Vol 658 ◽  
Author(s):  
Trong-Duc Doan ◽  
Cobey Abramowski ◽  
Paul A. Salvador

ABSTRACTThin films of NdNiO3 were grown using pulsed laser deposition on single crystal substrates of [100]-oriented LaAlO3 and SrTiO3. X-ray diffraction and reflectivity, scanning electron microscopy, and atomic force microscopy were used to characterize the chemical, morphological and structural traits of the thin films. Single-phase epitaxial films are grown on LaAlO3 and SrTiO3 at 625°C in an oxygen pressure of 200 mTorr. At higher temperatures, the films partially decompose to Nd2NiO4 and NiO. The films are epitaxial with the (101) planes (orthorhombic Pnma notation) parallel to the substrate surface. Four in-plane orientational variants exist that correspond to the four 90° degenerate orientations of the film's [010] with respect to the in-plane substrate directions. Films are observed to be strained in accordance with the structural mismatch to the underlying substrate, and this leads, in the thinnest films on LaAlO3, to an apparent monoclinic distortion to the unit cell.


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