Papers by Keyword: Magnetic Force Microscopy (MFM)

Abstract: This study presents the results of an analysis of the domain structure of supersaturated X2CoCrMoAl20-15-3 maraging steel. The analyses was carried out using the magnetic force microscopy method in a two pass mode. Obtained magnetic results were subjected to numerical analysis. The dimensions of spontaneously magnetized regions and their orientation were determined by analyzing the autocorrelation function of changes in the resonant frequency of the MFM probe. The use of fractal analysis was proposed to describe the domain structure.

Abstract: Contact lenses are a common optical aid to provide help with refractive anomalies of the human eye. Construction of contact lenses is a complex engineering task as it requires knowledge of optics, materials science, production and characterization methods for product quality. Besides correcting refractive anomalies, by using contact lenses it is possible to change the characteristics of light through the manipulation of material structure properties. Nanomaterials, such as fullerene C₆₀, are candidates for the medium that interacts with light, thus changing its properties. During material syntheses for contact lenses, fullerenes are added to the base material and optical characteristics of the new nanophotonic material are compared with the base material. The engineering, manufacture and characterization of both a commercial and a new nanophotonic contact lens is presented in this paper. The interaction of water with both base and nanophotonic contact lens materials is described. Using experimental techniques, the phenomena of an exclusion zone (EZ) is also identified.

Abstract: Magnetic Force Microscopy (MFM) and Opto-Magnetic Spectroscopy (OMS) were used to characterize HTCV stainless steel and aluminum. Both materials were immersed in 1.0M HCl and 1.0M CH₃COOH solutions for two hours. From the OMS method it was discovered that treated materials showed differences in peak wavelengths. Topographical and magnetic features for steel plate samples showed better resistance to an aggressive medium compared to aluminum. The results and analysis of these investigations are compared and presented in this paper.

Abstract: The quantitative analysis of static ferromagnetic correlations in nanocrystalline films Fe₇₈Zr₁₀N₁₂ was performed by two methods: the correlation magnetometry technique and magnetic force microscopy. The data, obtained by both methods, prove to be in good agreement.

Abstract: Recently carbon nanotubes (CNTs) are reported to be able to generate large magnetic field because of their nanometer-size-diameter[2]. The magnetic fields around CNTs current path are investigated by magnetic force microscopy (MFM). Under the consideration of the magnetic properties of magnetically coated tip of MFM, tip heights, current directions, and background magnetic field, etc., the magnetic field distribution are analyzed. The distribution of the magnetic field generated by the CNTs current is found to be asymmetric, and its distribution anomaly is found to be a kind of hysteresis effect of the MFM cantilever materials.

Abstract: A pair of magnetic domain walls (DWs) in ferromagnetic NiFe rings has been investigated in terms of the magnetic force microscopy (MFM). When the distance between the rings d is greater than a threshold value dth, MFM signals indicate that a DW in the ring is dragged due to a stray magnetic field from an MFM probe tip. When d < dth, this drag signals disappears; DWs are bound to each other by the DW-DW interaction. This transition can be argued in terms of the competition between the DW-DW magnetostatic interaction and the DW-drag potential. From the d-dependent MFM data, the DW-drag potential was estimated.

Abstract: Results obtained during examination of the multilayer Co/Au film by different methods of Magnetic Force Microscopy (MFM) are presented. It was shown, that double-pass scanning with MFM tips, characterised by strong magnetic moments resulted in a magnetisation reversal of the sample during MFM imaging. Single pass scanning or use of the MFM tips with low magnetic moments was required to minimise this process. Experimental results demonstrated good correlation between MFM results acquired during single-pass scanning and double-pass scanning with MFM tips characterised by low magnetic moment.

Abstract: Highly ordered arrays of Fe antidot films were fabricated by thermal vapor deposition technique using nanoporous alumina templates. The film thickness varies from 20 up to 100 nm, and the antidots array has about 50 nm in diameter and 105 nm of periodic interspacing. Scanning electron microscopy and atomic force microscopy measurements confirmed that the Fe antidots film retains the well-ordered hexagonal structure of the nanoporous alumina template. Meanwhile, the micromagnetic structure was studied by magnetic force microscopy and SQUID measurements. A stripe magnetic domain pattern featuring a large out-of-plane magnetization component is found in the films. Noteworthily, the magnetic domains are not pinned by the nanopores but, on the contrary, several antidots are included in each magnetic domain. According to the magnetic measurements, the easy magnetization axis of the Fe antidot array remains in the film plane, while the hard one lies perpendicular to the plane, which can be explained on the basis of the different contributions of the nanoholes to the total magnetic anisotropy of the antidots film.

Abstract: Co/Pt multilayers reside among the best candidates for perpendicular magneto-optic recording. In this work, Co/Pt multilayers were prepared by electron-beam evaporation under ultrahigh vacuum conditions on polyimide. X-ray diffraction measurements revealed the high quality of multilayer stacking. Magneto-optic polar Kerr effect experiments were used in order to obtain magnetization hysteresis loops of the films. We have studied the magnetic-domain morphology on the surface of the films via Magnetic Force Microscopy. The field applied during these measurements was 2.3 kOe oriented perpendicular to the film plane; this field seems to stabilize and enhance out-of-plain stripe domains against in plain domains that may be expected from magnetization curves. Finally, we observed that when the applied field approaches the magnetic saturation field, then the domain morphology turns to be dominated by bubble domains.

Abstract: Influence of structural transition in the evolution of the magnetic domains in the ferromagnetic shape memory alloy system Ni2+xMn1-xGa is reported here using Magnetic Force Microscopy (MFM) studies. Studies reported are with two samples with their martensite transition temperature TM less than and greater than the Curie temperature Tc. Present results show an evolution of MFM across the Tc with a clear twin domains and sub domain structures inside the twins. The higher spatial resolution of MFM (~50nm) as compared to optical microscope (400nm) is useful in probing the domain walls. Force derivative of the MFM signal that may be used as an order parameter seems to scale the onset of magnetic order in the system. One can clearly see the vanishing of the MFM patterns for T>Tc. Results are discussed in the light of models available for tip-sample interactions that track the local magnetization.