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The Magnetic Force Microscopy (MFM) combines the advantages of the Atomic Force Microscopy (AFM) with the ability to visualize the surface magnetic domain structure of samples. Higher contrast in the MFM imaging means better ability to see magnetic structures and distinguish them from noise. One of the parameters affecting the MFM image contrast is the free cantilever oscillation amplitude of the probe. In this study, we present MFM measurements performed on a magnetic videotape at two different levels of free cantilever oscillation amplitude. The results showed that scanning at higher amplitude can enhance the signal-to-noise ratio and thus the contrast of the MFM image. Conversely, scanning at lower amplitude increases the perception level of the noise in the image. However, it should be noted that in the scope of our experimental conditions, changes in the image were not significant. In addition, it was found that precise adjustment of the tip-to-surface distance plays a crucial role in this MFM experiment, which is not the same as the "lift height" parameter. [ABSTRACT FROM AUTHOR]

Cobalt ferrite fibers were synthesized by electrospinning technique. The structural studies were analyzed by X-ray diffraction (XRD), which showed an average crystallite size of 34 nm. Morphology of CoFe2O4 fibers was studied using transmission electron microscopy (TEM) and atomic force microscopy (AFM), which revealed the formation of fibers with average fiber diameter of 220 nm. Further the magnetic behavior of the CoFe2O4 was investigated using magnetic force microscopy (MFM). MFM clearly showed fiber structure with the domain orientation of magnetic moment in downward direction. [ABSTRACT FROM AUTHOR]

In order to characterize magnetic properties of cobalt-based nanoparticles synthesized through electrodeposition on metal substrates, methods must be employed which enable the imaging of sample surface, the selection of a specific nanoparticle, and the accurate evaluation of local magnetic parameters, such as magnetic moment or saturation magnetization. Due to the combination of imaging capability and quantitative probing of ultra-low magnetic field through the use of a nanometer sized tip with a magnetic coating, magnetic force microscopy (MFM) is a promising tool to characterize Co-based nanoparticles directly on substrates. In this work, the report the preliminary results of the use of MFM to analyze Co nanoparticles electrodeposited on an Al substrate. The aim wa to assess the effective capability of this technique to investigate this kind of nanomaterials, foresee offered possibilities, and highlight current limitations to overcome. [ABSTRACT FROM AUTHOR]

Si-ion irradiation assisted modifications of structural, magnetic properties of (Fe40Co60)84.5Nb5B8.5P2 alloy have been examined by synchrotron x-ray diffraction, atomic force microscopy and magnetic measurements. Results show: i) short range order remains un-affected, ii) evidences of enhanced medium range ordering, which affects magnetic properties, iii) irradiation influences grain diameter, volume fraction of formed nano-grains, respectively between 5.9−6.5nm, 8−10%, iv) changes were observed in surface roughness and height. An empirical relation is achieved showing parabolic dependency between inter-atomic distances for 2nd, 3rd co-ordination shell with magnetization, implying strong correlation among structural, magnetic properties. [ABSTRACT FROM AUTHOR]

Extensive use of digital and smartcommunication creates prolong expose of unwanted electromagnetic (EM) radiations. This can not only create malfunctioning of nearby electronic gadgets but also reported that it can affect human health in several ways. Therefore, a suitable microwave absorbing material (MAM) becomes a necessary requirement in the field of stealth and radar technology. In the present work aluminum based hexaferrite phase conjugated with graphene inPoly (Vinyelfluoride) matrix has been tested in X and Ku band for absorption properties. The structural and morphological nature was characterized by X-Ray diffraction (XRD), Field emission-scanning electron microscope (FESEM) and Raman spectra which conforms that 30-100 nm particles are well decorated over graphene sheet. Magnetic force microscopy (MFM) conforms the magnetic nature of composite. Finally, shielding effectiveness (SE) of composite film was studied by using Vector network analyser (VNA) both in X band and Ku band frequency range and found to be more than 30 dB and 40 dB, respectively. [ABSTRACT FROM AUTHOR]

Electrostatic tip-sample interactions currently represent the main limitation to accurate quantitative analysis of magnetic force microscopy (MFM) data. Controlled magnetization MFM (CM-MFM) represents a smart solution to overcome this limitation as it allows one to identify electrostatic artifacts and to subtract them from standard MFM images, thus enabling the quantitative investigation of magnetic properties of materials at the nanometer scale. CM-MFM, however, requires not only the magnetization, but also the in situ accurate demagnetization of the MFM probe. In particular, the latter represents a crucial step for the complete removal of electrostatic artifacts. In this work, we describe two different methods to depolarize the MFM tip, based on the application of the coercive remanent magnetic field of the tip and on a damped alternating magnetic field, respectively. The two techniques are escribed and compared to emphasize their specific advantages and limitations. [ABSTRACT FROM AUTHOR]

Magnetic nanoparticles (MNPs) represent an interesting tool for several biomedical applications. In order to improve the dispersion stability, the biocompatibility and bio-functionality, MNPs need to be coated with non-magnetic films. The optimization of these systems requires the deep characterization not only of the magnetic core, but also of the coating features. Beside the chemical and physical properties of the coating, its thickness is another important property which can influence the size, the shape and the overall magnetic behavior of the NPs system. In this work we propose a possible method to measure the thickness of the non-magnetic coating of core-shell MNPs through the use of controlled magnetization-magnetic force microscopy (CM-MFM). A preliminary study on the applicability of the proposed method has been performed on Fe3O4 NPs coated with a Cu film. [ABSTRACT FROM AUTHOR]

In this communication, we report the rectifying properties observed across the junction, consists of Ca+2 doped hexagonal YMnO3 manganite film, grown on n-type (100) Si single crystalline substrate. The junction was grown using cost effective chemical solution deposition (CSD) technique by employing spin coating method. Surface morphology of Y0.95Ca0.05MnO3/Si (YCMO/Si) film was carried out by atomic force microscopy and magnetic response of film was studied by magnetic force microscopy. Current - voltage characteristics of the junction was carried out by using Keithley source meter in current perpendicular to plane (CPP) mode at different temperatures. Rectification in I - V behavior has been observed for the junction at all the temperatures studied. With increase in temperature, rectification ratio, in the range of 104, increases across the junction. Results have been discussed in the context of thermal effects. [ABSTRACT FROM AUTHOR]

The paper presents the results of the comparative study of the possibilities of different structural and magnetic methods for detection and visualization of the strain-induced martensitic phase in low carbon austenitic chromium-nickel steel. Results of TEM, SEM, optical microscopy, atomic and magnetic force microscopy, and magnetic measurements are presented. Amount of the magnetic strain-induced martensite was estimated. We pioneered magnetic force microscopic images of the single domain cluster distribution of the strain-induced martensite in austenite-ferrite materials. [ABSTRACT FROM AUTHOR]

The development of magnetic nanoparticles for biomedical applications requires a detailed characterization of their magnetic properties, with relation not only to their chemical structure, but also their morphology and size. Magnetic force microscopy (MFM), thanks to its nanometric lateral resolution and its capability to detect weak magnetic fields, appears as a powerful tool for the characterization of the magnetic properties of single nanoparticles, together with their morphological characteristics. Nevertheless, the application of MFM to the quantitative measurements of magnetic properties at the nanoscale is still an open issue because of a certain incongruence between experimental data and existing theoretical models of the tip- sample magnetic interactions. In this work, MFM data acquired on different magnetic nanoparticles in different experimental conditions (magnetized and not magnetized probes, out-of-field and in-field measurements) are analyzed, with the aim of individuating the possible phenomena affecting MFM measurements. These include topography-induced artifacts resulting from the tip-sample capacitive coupling, which we propose here for the first time. In case of measurements performed in presence of an external magnetic field, much more intense MFM signals were detected as it produces the saturation of the magnetization of the nanoparticles, which is not completely obtained by the sole stray field produced by the tip. Nevertheless, even in in-field measurements, the results evidenced the presence of significant electrostatic effects in MFM images, which, therefore, appear as an important factor to be taken into account for the quantitative interpretation of MFM data. [ABSTRACT FROM AUTHOR]

We report a phenomenological approach for the quantification of the diameter of magnetic nanoparticles (MNPs) incorporated in non-ionic surfactant vesicles (niosomes) using magnetic force microscopy(MFM). After a simple specimen preparation, i.e., by putting a drop of solution containing MNPs-loaded niosomes on fiat substrates, topographyand MFM phase images are collected. To attempt the quantification of the diameter of entrapped MNPs, the method is calibrated on the sole MNPs deposited on the same substrates by analyzing the MFM signal as a function of the MNP diameter (at fixed tip-sample distance) and of the tip-sample distance (for selected MNPs). After calibration, the effective diameter of the MNPs entrapped in some niosomes is quantitatively deduced from MFM images. [ABSTRACT FROM AUTHOR]

The temperature driven first order AFM to FM phase transition of Rh doped FePt is studied during cooling and heating across the transition temperature by magnetic force microscopy. During warming AFM to FM transition starts with the nucleation of micrometer size nuclei of FM phase, which grows gradually with increase in temperature. The reverse transformation also takes place in similar fashion resulting in a phase co-existence of AFM FM phase on micrometer length scale over a wide temperature range. [ABSTRACT FROM AUTHOR]

The formation of a cementite phase influences significantly the macroscopic mechanical and magnetic properties of steels. Based on a correlation between mechanical and magnetic properties, mechanical properties as well as the morphology and content of the cementite phase can be inspected by electromagnetic non-destructive testing methods. The influence of the carbon content on bulk magnetic properties of unalloyed steels is studied on a macroscopic scale by hysteresis loop and Barkhausen noise measurements. The micro- and nanostructure is investigated by atomic force microscopy and magnetic force microscopy. Surface topography images and magnetic images of globular cementite precipitates embedded in a ferrite matrix are presented. The size, shape, and orientation of the precipitates influence the domain configuration. Applied external magnetic fields cause magnetization processes mainly in the ferrite matrix: Bloch walls move and are pinned by the cementite precipitates. The correlation between the microscopic observations and macroscopic magnetic properties of the material is discussed. [ABSTRACT FROM AUTHOR]

We have been successful in developing Bi0.7Dy0.3FeO3 (BDFO) material which exhibits the multiferroic behavior at room temperature with significant coupling in bulk as well as thin films. If this material could be fashioned as nanorod, implementation in devices could be more straight forward. We have therefore used vertically aligned arrays of silicon rods (∼5 μm in length and ∼0.5 μm in diameter) as template to direct the growth of a uniform layer of the BDFO on the surface of the Si rods by using pulse laser deposition technique. XRD results indicate presence of phase pure BDFO layer on Si. Magnetic properties of BDFO/Si rods were studied by using VSM. M-H curve indicates the ferromagnetic behaviour of the rods at room temperature. Magnetic force microscopy (MFM) was used to study the magnetic domain structure of the individual BDFO/Si rod. [ABSTRACT FROM AUTHOR]

Remenance and coercivity in Nd2Fe14B materials are strongly dependent on the microstructural aspects like phases morphology and grain size. The coercivity (Hc) of a magnetic material varies inversely with the grain size (D) and there is a critical size below which Hc∝D6. Domain wall pinning by grain boundaries and foreign phases is the important mechanism in explaining the improvement in coercivity and remenance. Nd2Fe14B intermetallic compound with stochiometric composition was prepared from pure elements (Nd -99.5%, Fe—99.95%, B -99.99%) by arc melting in argon atmosphere. Magnetic Force Microscope (MFM) gives high-resolution magnetic domain structural information of ferromagnetic samples. DI-3100 Scanning Probe Microscope with MESP probes was used For MFM characterization of the samples. Magnetic domains observed in cast ingots were very long (up to 40 μm were observed) and approximately 1–5 μm wide due to high anisotropy of the compounds. Magnetic domains have displayed different image contrast and morphologies at different locations of the samples. The domain morphologies and image contrast obtained in this analysis were explained in this paper. [ABSTRACT FROM AUTHOR]

We report the observation of complex ferromagnetic domain structures on thin films of SrRuO3 and superconducting vortices in high temperature superconductors through low temperature magnetic force microscopy. Here we summarize the experimental details and results of magnetic imaging at low temperatures and high magnetic fields. We discuss these data in the light of existing theoretical concepts. [ABSTRACT FROM AUTHOR]

Polycrystalline Ni-Mn-Ga thin films have been deposited on Si (100) substrate with different film thickness. The influence of film thickness on the phase structure and magnetic domain of the films has been examined by scanning electron microscope, atomic force microscopy and magnetic force microscopy. Analysis of structural parameters indicates that the film at lower thickness exhibits the coexistence of both austenite and martensite phase, whereas at higher thickness L12 cubic non magnetic phase is noticed. The grains size and the surface roughness increase along with the film thickness and attain the maximum of 45 nm and 34.96 nm, respectively. At lower film thickness, the magnetic stripe domain is found like maze pattern with dark and bright images, while at higher thickness the absence of stripe domains is observed. The magnetic results reveal that the films strongly depend on their phase structure and microstructure which influence by the film thickness. [ABSTRACT FROM AUTHOR]

A magnetic force microscope has been constructed to image fluxlines in superconductors. In order to facilitate operation at low temperatures, cantilever deflections are detected with an interferometer which requires only an optical fibre in the cryostat. The design and modes of operation of the microscope are described. Room temperature AFM and MFM images are presented. The MFM results, combined with planned experimental improvements, point towards future success in imaging fluxlines. © 2003 American Institute of Physics [ABSTRACT FROM AUTHOR]

We present the development of a probe for scanning probe microscopy and recording, called the CantiClever. This probe is designed to address the issue of the less than ideal tip geometry of conventional MFM tips and to allow the integration of other sensors other than an MFM tip with relative ease. Simulations of the influence of the tip-end shape on the tip’s transfer function indicate that an ellipsoidal shape results in the highest possible resolution because of the absence of zero-signal frequencies in the tip’s spatial frequency response. Furthermore, the magnetic domain structure of the tip was investigated with the use of MFM. It was determined that the tip, once magnetized, consists of one single magnetic domain. To exploit the capability for sensor integration, a magneto resistive element was integrated on the probe. This type of probe can be used in scanning probe microscopy and recording. © 2003 American Institute of Physics [ABSTRACT FROM AUTHOR]

The resolution of a magnetic force microscope with metal-capped nanotube probes has been investigated from the theoretical and experimental points of view. The width of the line image of the magnetic information was measured as a function of the tip-sample separation using a nanotube probe with a particle of Fe3C with a diameter of 50 nm. The theoretical calculation, which well explains this experimental result, indicates that the metal-capped nanotube probes have a high potential for the high resolution imaging of the magnetic information. The resolution less than 10 nm is obtained when the nanotube tip with a diameter of ∼ 10 nm is scanned with the tip-sample separation of ∼ 10 nm. © 2003 American Institute of Physics [ABSTRACT FROM AUTHOR]

We introduce a new method to perform sequential measurements of the in-plane and out-of-plane magnetic force gradient components using the same topographic scan lines to preserve geometrical position registry at the nanometer scale. This method applies both flexural and torsional resonant oscillations of the same atomic force microscope cantilever probe for the determination of respective vertical and lateral force gradient components in a sequence of scans. Using magnetic domains in a hard drive with known stray field, as simulated by finite element analysis, we have demonstrated that the two oscillation modes provide complementary information about the orientation of the magnetic momentum of the probe tips. The matching of both vertical and lateral force gradient data with that of the finite element simulation occurs only at a unique orientation of tip magnetization. Furthermore, it was found that force gradient measurements using torsion mode are able to determine in-plane anisotropy. © 2003 American Institute of Physics [ABSTRACT FROM AUTHOR]

We report the use of piezoelectric quartz tuning forks as force sensors for variable temperature magnetic force microscopy. As the Q-factor of the sensor alters with temperature we have investigated the effect of electronically varying the Q-factor at constant temperature to elucidate how the sensitivity of the sensor depends on the Q-factor. We find that the sensitivity improves in proportion to the Q-factor. The signal-to-noise ratio also improves as the Q-factor is increased. © 2003 American Institute of Physics [ABSTRACT FROM AUTHOR]

A computer analysis of MFM images of separate ferromagnetic single-domain nanoparticles placed on a nonmagnetic substrate was carried out. The shape of an MFM tip and the trajectory of its movement were taken into account. The aureoles were found in the magnetic contrast of MFM images simulated for the lifting mode. The conditions and the reasons of the appearance of these aureoles were discussed. © 2003 American Institute of Physics [ABSTRACT FROM AUTHOR]

The local modification of the antiferromagnetic interlayer coupling in the epitaxial Fe/Cr/Fe (001) trilayer systems by focused ion beam irradiation has been studied experimentally. It is shown that using the ion fluencies of 1015 ions/cm2 it is possible to achieve a complete local transformation of the antiferromagnetic coupling between two Fe films to the ferromagnetic one. As a result of focused ion beam irradiation square ferromagnetic areas (200×200 μm2) were created on the initially antiferromagnetically coupled trilayer. These areas were studied using the magnetic force microscope in order to determine how abrupt is the change of magnetic properties at the boundary between the irradiated and non-irradiated areas. MFM measurements have shown that in the range of external magnetic field of about ±200 Oe the magnetic boundary between the areas is very well defined. The later allows using the ion irradiation for magnetic patterning of Fe/Cr/Fe trilayers on the micrometer and submicrometer scale. © 2003 American Institute of Physics [ABSTRACT FROM AUTHOR]

The magnetic field gradients of magnetic stripe cards, which are developed for classifying magnetic particles used in magnetic particle inspections, have been measured using a magnetic force microscope (MFM). The magnetic force exerted on a MFM probe by the stray field emanating from the card was measured to determine the field gradients. The results are in good agreement with the field gradients estimated from the magnetizing field strengths used in the encoding process. [ABSTRACT FROM AUTHOR]

The study of electromigration in metals requires correlation of current densities with the evolution of defects in current-carrying lines. In principle, magnetic force microscopy (MFM) is an appropriate probing tool that will allow us to directly image the curvature of the magnetic fields around defect structures and thus deduce the underlying current densities. Previous use of MFM in research has concentrated upon determining magnetic polarity, such as that across magnetic domain boundaries, and there has been little evaluation of MFM capability to make meaningful quantification. To explore the MFM capability to yield reliable analysis, we are carefully evaluating the MFM instrument response for known structures, such as that around lines containing defects of simple geometry. The instrumental response function is defined by tip parameters, such as tip magnetization and shape, which make absolute quantification impractical, but it is possible to make meaningful relative quantification and calibration, by comparison with response from structures where the behavior is well understood. To analyze the data from such known calibration samples, the fields around the lines are numerically calculated and compared with deconvolution of the measured signal to help us determine the validity of our MFM response. Preliminary results suggest that meaningful relative quantification of the signal can be achieved to within 10%. [ABSTRACT FROM AUTHOR]

Magnetic domains in the ferrimagnetic state of Co doped Mn2Sb single crystal has been visualized using Magnetic Force Microscopy. It shows fractal like domain structure. With the application of magnetic field, single domain state is achieved around 2000 Oe. The MFM images collected during field increasing and decreasing cycles show different morphology for same field value. [ABSTRACT FROM AUTHOR]

We present here the effects of Swift heavy ion (SHI) irradiation with 200 MeV Ag15+ ions on the structural properties of GdFeO3 epitaxial film grown on SrTiO3 (STO) substrate with (001) orientation by pulsed laser deposition (PLD). The irradiation of the film induces lattice expansion in c-axis and increases the surface roughness as compared to the pristine film, which is estimated from root mean square value of Atomic Force microscopic (AFM) images. Also an enhancement in the phase contrast for SHI irradiated film is noticed from magnetic force microscopy (MFM) images. [ABSTRACT FROM AUTHOR]

In this paper, magnetic properties of Fe/Cu/Fe, Fe/Cr/Fe Fe/Al/Fe (Ferromagnetic/Metal/Ferromagnetic) sandwitch thin films have been studied. The magnetic properties were investigated by magnetic force microscopy (MFM) alternative gradient force magnetometery (AGFM) analysis. The structure of the mentioned sandwiches was investigated using X-ray diffraction (XRD) analysis. An X-ray diffractometer with Cu-Kα radiation (λ = 1.5405 Å) was used, in a Bragg-Brentano arrangement and atomic force microscopy. Morphological and structural studies show that the nanoparticles grow in a well-defined nanostructured pattern. [ABSTRACT FROM AUTHOR]

We investigate magnetic domain structures of La0.625Ca0.375MnO3 on NGO (110)by means of low temperature magnetic force microscopy (MFM). On zero field cooling below 230 K, domains start appearing in the form of regular stripes suggesting out of plane magnetization of the film. The stripe pattern disappears as a spin reorientation transition makes the bulk magnetization lie on the plane of the film. [ABSTRACT FROM AUTHOR]

We have reported the formation of magnetic and non magnetic regime in the same sample by oblique incidence 36 keV Fe3+ ion bombardment on Si(100) ripple structures prefabricated by 8 keV O1+ bombardment at oblique angle. The same phenomenon is also observed on ion induced rippled ZnO thin films deposited of on Si(100). Ex situ atomic force microscopy (AFM) and magnetic force microscopy (MFM) measurements reveals the development of ripple structure and magnetic regime. [ABSTRACT FROM AUTHOR]

The magnetic anisotropy of epitaxial InMnAs thin films have been studied using the longitudinal magneto-optical Kerr effect and magnetic force microscopy at room temperature. Square hysteresis loops were obtained for phase pure layers grown on InAs and GaAs substrates. InMnAs layers on GaAs possess magnetic in-plane isotropy as evidenced by hysteresis loops that were independent of in-plane rotations. On the other hand, InMnAs layers on InAs exhibit strong two-fold in-plane anisotropy. The easy axis of magnetization is along the [110] and [110] directions. In addition in-plane elliptical domains predominantly aligned along the easy axis were observed by magnetic force microscopy. The observed uniaxial in-plane anisotropy is attributed to the presence of unrelaxed coherency strain in InMnAs films grown on InAs. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]