Multimode Scanning Probe Microscopy Research Articles

Multiferroic properties and surface potential behaviors in cobalt-doped BiFeO3 film

The spatial coexistence of magnetic and ferroelectric domains in multiferroic BiFe0.96Co0.04O3 film is confirmed by multimode scanning probe microscopy. The applied bias dependence of the surface potential in BiFe0.96Co0.04O3 indicates that surface potential is determined by the interplay of polarization and surface charges. It is also shown that multiferroic BiFe0.96Co0.04O3 can more easily trap surface charges than the well-known ferroelectric PbZr0.53Ti0.47O3. The time evolution of surface potential exhibits an exponential decay, which is closely related to the observed spread of surface charges. The study on BiFe0.96Co0.04O3 unveils the origin and evolution behavior of the surface potential in BiFeO3-based multiferroic films.

A minilaboratory for education and the first steps of R&D in nanotechnology based on the nanoeducator scanning probe microscope

The peculiarities of a minilaboratory based on the Nanoeducator multimode scanning probe microscope (http://www.ntmdt.ru/platform/nanoeducator), which has been used for training nanotechnology specialists in over 70 higher educational institutions throughout Russia and in over 40 centers worldwide, are described. The constructive features of the instrument and its possibilities for measuring and in lithography are described.

Observation of magnetoelectric coupling in Bi0.7Dy0.3FeO3 thin films at room temperature

Spatial coexistence of ferroelectric and magnetic domains in micrometer scale is confirmed by multimode scanning probe microscopy of pulsed laser deposited Bi0.7Dy0.3FeO3 thin films. The observed change in ferroelectric polarization with applied magnetic field proves the coupling between magnetic and ferroelectric order parameters. Moreover, the alignment of magnetic domains with externally applied electric field further confirms the presence of coupling in this system. Remarkably, the effect persists even after the electric field is removed, thereby implying an electric field induced magnetic hysteresis phenomenon in the magnetic domain structure. The results suggest an in-principle usability of this system for multifunctional applications.

SPM Characterization of Pulsed Laser Deposited Nanocrystalline CrN Hard Coatings

Nanocrystalline CrN coatings, widely required for surface engineering application covering wear and corrosion resistance, need to be investigated for atomic scale morphology, surface roughness, local stiffness, phase uniformity, and homogeneity. Evolution of these properties as a function of thickness need to be studied. In this paper, we have attempted to address these issues through use of a multimode scanning probe microscope (SPM) equipped to carry out Atomic Force Microscopy (AFM) and Atomic Force Acoustic microscopy (AFAM) of Chromium nitride films (100-500 nm thick) on Si prepared under high vacuum by pulsed Laser Ablation using Nd-YAG Q-switched laser. Prior to SPM analysis, the coatings were annealed in N2 atmosphere at 700 degrees C for 30 minutes for improving crystallanity and coating substrate adhesion. The GIXRD patterns of these annealed specimens showed formation of nanocrystalline CrN. Also signature of amorphous phases was seen. The grain size was estimated to be less than 30 nm. Contact mode AFM imaging revealed a roughness value less than 50 nm. Local stiffness values were calculated from AFM force-distance curves. Imaging of frictional force and surface flaws are being investigated by Frictional Force Microscopy (FFM), resonance spectroscopy, and AFAM, respectively. The contrast in AFAM images is seen due to variation in surface elasticity in reference and CrN samples. Stiffness constant and elastic modulus were calculated for both the samples and compared.

Stripe domain analysis of alkanethiol and alkynethiol monolayers self-assembled on the surfaces of gold grains

The self-assembled monolayers (SAMs) of alkanethiols such as 1-dodecanethiol (DDT) on the surface of polycrystalline gold grain on quartz crystal microbalance (QCM) at room temperature and alkynethiols such as phenylethynyl thiol (PET) on the surface of Au(111)/mica under − 65 °C have been fabricated. A multimode scanning probe microscope (SPM) investigation for the first time reveals the formation of stripe domain of DDT SAMs together with roundish domain. This feature was not caused by an annealing treatment but might be induced by coexistence of a few different facets and reconstruction of the surface on the grain. The stripe domain of PET SAMs could also be found on the surface of the grain, which was within the substrate of the gold/mica. It shows that the feature of the stripe domain for organothiol monolayers self-assembled on gold grain surfaces possesses a certain generality. Furthermore, the arrangement of organothiol stripe domain can be well understood from the interpretation of the relationship between the stripe width and width direction, molecule interval distance, molecule length and tilt angles of the thiols.

Quantifying the Specific Binding between West Nile Virus Envelope Domain III Protein and the Cellular Receptor αVβ3 Integrin

A previous study has illustrated that the alphaVbeta3 integrin served as the functional receptor for West Nile virus (WNV) entry into cells. Domain III (DIII) of WNV envelope protein (E) was postulated to mediate virus binding to the cellular receptor. In this study, the specificity and affinity binding of WNV E DIII protein to alphaVbeta3 integrin was confirmed with co-immunoprecipitation and receptor competition assay. Binding of WNV E DIII protein to alphaVbeta3 integrin induced the phosphorylation of focal adhesion kinase that is required to mediate ligand-receptor internalization into cells. A novel platform was then developed using the atomic force microscopy to measure this specific binding force between WNV E DIII protein and the cellular receptor, alphaVbeta3 integrin. The single protein pair-interacting force measured was in the range of 45 +/- 5 piconewtons. This interacting force was highly specific as minimal force was measured in the WNV E DIII protein interaction with alphaVbeta5 integrin molecules and heparan sulfate. These experiments provided an insight to quantitate virus-receptor interaction. Force measurement using atomic force microscopy can serve to quantitatively analyze the effect of candidate drugs that modulate virus-host receptor affinity.

Surface viscoelasticity studies of Gd 2O 3, SiO 2 optical thin films and multilayers using force modulation and force–distance scanning probe microscopy

The single and multilayer of Gd 2O 3 and SiO 2 thin films deposited through reactive electron beam evaporation have been studied for their viscoelasticity properties and optical spectral stability using multimode scanning probe microscope and spectrophotometric techniques. A conspicuous changes in viscoelasticity properties and surface topographies have been observed with the Gd 2O 3 films deposited under various oxygen pressures. The scanning probe measurements on the multilayer filters fabricated using these film materials for laser wavelengths of 248 nm (KrF) and 355 nm (Nd:Yag-III) have shown superior viscoelasticity property, which is not the case with the most conventional multilayers. The results were correlated with the long-term spectral stability that has been studied by recording transmittance spectra of these filters at a time interval of 10 months. Both the multilayer filters have shown excellent temporal spectral stabilities with a relatively better result for the 248 nm reflection filter. Further analysis has shown a very good co-relationship in the spectral stability and viscoelasticity properties in these multilayers.

Nanofabrication using computer-assisted design and automated vector-scanning probe lithography

This work represents our initial effort towards the fabrication of complex nanopatterns with automated scanning probe lithography (SPL). A multi-mode scanning probe microscope is linked with a computer-controlled vector-scan module to allow precise, automated control of the tip motion. The module is interfaced with computer-assisted design (CAD) and VLSI software, and programming capabilities are developed. We also provide a pathway for integration of our apparatus with external instruments. The capability to rapidly produce complicated nanopatterns is demonstrated using AFM fabrication of thiol self-assembled monolayers.

Nanoscale design of snake skin for reptation locomotions via friction anisotropy

Multi-mode scanning probe microscopy is employed to investigate the nanostructure of dermal samples from three types of snakes. Sophisticated friction modifying nanostructures are described. These include an ordered microfibrillar array that can function to achieve mission adaptable friction characteristics. Significant reduction of adhesive forces in the contact areas caused by the ‘double-ridge’ nanoscale microfibrillar geometry provides ideal conditions for sliding in forward direction with minimum adhesive forces and friction. Low surface adhesion in these local contact points may reduce local wear and skin contamination by environmental debris. The highly asymmetric, ‘pawl-like’ profile of the microfibrillar ends with radius of curvature 20–40 nm induces friction anisotropy in forward–backward motions and serves as an effective stopper for backward motion preserving low friction for forward motion. The system of continuous micropores penetrating through the snake skin may serve as a delivery system for lubrication/anti-adhesive lipid mixture that provides for boundary lubrication of snake skins.