共查询到20条相似文献,搜索用时 31 毫秒
1.
Sang-Jun Choi Young-Jin Cho Soo-haeng Cho Jung-hwan Moon 《Journal of magnetism and magnetic materials》2010,322(3):332-336
We demonstrate ultra-high-resolution magnetic force microscopy images of perpendicular magnetic storage media using carbon nanotube probes coated by ferromagnetic Co90Fe10 films (20, 30, 40, and 50 nm). By optimizing ferromagnetic film thickness (effective tip diameter), we obtained best magnetic domain image with an 40 nm-Co90Fe10-coated tip (50 nm tip diameter) about a lateral detect density of 1200 k flux per inch on perpendicular magnetic storage medium, one of the highest resolutions in MFM imaging reported for this material system and structure. The observed dependence of tip dimension on signal contrast and image resolution was successfully explained by a theoretical analysis indicating that the signal contrast, along with the physical probe-tip dimension, should be taken into account to design magnetic probes tips for high-resolution magnetic force microscopy. 相似文献
2.
V. L. Mironov D. S. Nikitushkin D. S. Petrov A. B. Shubin P. A. Zhdan 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2007,1(3):348-351
Calculations of the magnetic force microscopy (MFM) contrast from low-coercive ferromagnetic and superparamagnetic particles are presented. It is shown that the external field stabilizes the magnetic moment of particles, allowing the separation of contributions of van der Waals and magnetic interactions to the MFM phase contrast. The values of stabilizing magnetic fields are estimated. 相似文献
3.
Fritzsche J Moshchalkov VV Eitel H Koelle D Kleiner R Szymczak R 《Physical review letters》2006,96(24):247003
Nanoscale magnetic and superconducting properties of the superconductor-ferromagnet Nb/PbFe12O19 hybrid were studied as a function of applied magnetic fields. Low-temperature scanning laser microscopy (LTSLM) together with transport measurements were carried out in order to reveal local variations of superconductivity induced by the magnetic field template produced by the ferromagnetic substrate. Room temperature magnetic force microscopy (MFM) was performed and magnetization curves were taken at room and low temperature to investigate the magnetic properties of the hybrid. Comparative analysis of the LTSLM and the MFM images has convincingly demonstrated the presence of the reverse-domain superconductivity. 相似文献
4.
Joonyeon Chang Hyunjung Yi Hyun Cheol Koo V.L. Mironov B.A. Gribkov A.A. Fraerman S.A. Gusev S.N. Vdovichev 《Journal of magnetism and magnetic materials》2007
We investigated remagnetization processes in ferromagnetic nanoparticles under inhomogeneous magnetic field induced by the tip of magnetic force microscope (MFM) in both theoretical and empirical ways. Systematic MFM observations were carried out on arrays of submicron-sized elliptical ferromagnetic particles of Co and FeCr with different sizes and periods. It clearly reveals the distribution of remanent magnetization and processes of local remagnetization of individual ferromagnetic particles. Modeling of remagnetization processes in ferromagnetic nanoparticles under magnetic field induced by MFM probe was performed on the base of Landau–Lifshitz–Gilbert equation for magnetization. MFM-induced inhomogeneous magnetic field is very effective to control the magnetic state of individual ferromagnetic nanoparticles as well as to create different distribution of magnetic field in array of ferromagnetic nanoparticles. 相似文献
5.
D. O. Filatov E. I. Malysheva 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2007,1(3):352-358
The dependence of magnetic properties of GaAs:Mn and MnAs epitaxial films grown on GaAs (001) by laser ablation of Mn and undoped GaAs in a hydrogen atmosphere under the growth conditions has been studied by magnetic force microscopy (MFM). Magnetic probe calibration for quantitative MFM measurements was performed by scanning across the slit of the magnetic-head of a tape recorder through which controlled direct current was passed. The dipole approximation was used to describe the magnetic properties of the MFM probe. Nonuniformity of the magnetization of GaAs:Mn films related to the formation of MnAs nanoinclusions, which are ferromagnetic at 300 K, has been observed. The typical scales of the spatial nonuniformity of the magnetization of GaAs:Mn films were varied from 270 to 550 nm depending on the film-growth conditions. The MnAs phase was identified by MFM measurements at an elevated temperature (up to 80°N). 相似文献
6.
近年来磁力显微镜(magnetic force microscopy,MFM)对动态磁场信号的测量与分析由于其特殊的工业要求和重要用途而受到广泛关注,本文旨在利用交变磁力对磁性探针的周期性调制发展一种交变力磁力显微镜技术,为磁信息存储工业等重要领域关键技术的发展提供新型的有力的工具.与目前标准MFM采用的设计思路不同,本文的关键在于合理利用MFM频率调制机理,优化设计MFM磁性探针,并且引入动态信号处理模块,实现对交变磁场信号的MFM成像.为达到这些目的,需要从理论上研究MFM探针的频率调制机理,并由实验上设计出动态信号提取模块,二者相辅结合优化设计出具有动态信号测试和分析能力的交变力磁力显微镜技术,由此来测量和解释纳米尺度磁畴结构. 相似文献
7.
An investigation of phase separation by magnetic force microscopy in La0.45Sr0.55MnO3-δ(δ≈0.01) 下载免费PDF全文
We have found phase separation in La0.45Sr0.55MnO3-δ (LSMO) by means of electron spin resonance, magnetic force microscopy (MFM) and magnetic measurements. Ferromagnetic and antiferromagnetic phases can coexist at low temperatures, and ferromagnetic and paramagnetic phases coexist when the temperature lies between the Néel and Curie temperatures. The size and shape of the ferromagnetic phases (the minority phases) was first observed directly from MFM images. It is suggested that the phase separation in LSMO is not the charge segregation type, but an electroneutral type due perhaps to the nonuniform distribution of oxygen vacancies. 相似文献
8.
Highly ordered composite nanowires with multilayer Ni/Cu and NiFe/Cu have been fabricated by pulsed electrodeposition into
nanoporous alumina membrane. The diameter of wires can be easily varied by pore size of alumina, ranging from 30 to 100 nm.
The applied potential and the duration of each potential square pulse determine the thickness of the metal layers. The nanowires
have been characterized by transmission electron microscopy (TEM), magnetic force microscopy (MFM), and vibrating sample magnetometer
(VSM) measurements. The MFM images indicate that every ferromagnetic layer separated by Cu layer was present as single isolated
domain-like magnet. This technique has potential use in the measurement and application of magnetic nanodevices. 相似文献
9.
Fast and efficient software tools previously developed in image processing were adapted to the analysis of raw datasets consisting of multiple stacks of images taken on a sample interacting with a measuring instrument and submitted to the effect of an external parameter. Magnetic force microscopy (MFM), a follow-up of atomic force microscopy (AFM), was selected as a first testbed example. In MFM, a specifically developed ferromagnetic scanning tip probes the stray magnetic field generated from a ferromagnetic specimen. Raw scanning probe images taken on soft patterned magnetic materials and continuous thin films were used, together with synthetic patterns exploited to assess the absolute performance ability of the proposed texture analysis tools. In this case, the parameter affecting the sample-instrument interaction is the applied magnetic field. The application discussed here is just one among the many possible, including, e.g., real-time microscopy images (both optical and electronic) taken during heat treatments, phase transformations and so on. Basically any image exhibiting a texture with a characteristic spatial or angular dependence could be processed by the proposed method. Standard imaging tools such as texture mapping and novel data representation schemes such as texture analysis, feature extraction and classification are discussed. A magnetic texture stability diagram will be presented as an original output of the entropic analysis on MFM datasets. 相似文献
10.
Schmid I Marioni MA Kappenberger P Romer S Parlinska-Wojtan M Hug HJ Hellwig O Carey MJ Fullerton EE 《Physical review letters》2010,105(19):197201
For a fixed 2 μm×2 μm area of a Co/Pt-CoO perpendicular exchange bias system we image the ferromagnetic (FM) domains for various applied fields with 10-nm resolution by magnetic force microscopy (MFM). Using quantitative MFM we measure the local areal density of pinned uncompensated spins (pinUCS) in the antiferromagnetic (AFM) CoO layer and correlate the FM domain structure with the UCS density. Larger applied fields drive the receding domains to areas of proportionally higher pinUCS aligned antiparallel to FM moments. The data confirm that the evolution of the FM domains is determined by the pinUCS in the AFM layer, and also present examples of frustration in the system. 相似文献
11.
V. Cambel P. Eliáš J. Martaus G. Karapetrov 《Journal of magnetism and magnetic materials》2010,322(18):2715-2721
Using combination of micromagnetic calculations and magnetic force microscopy (MFM) imaging we find optimal parameters for novel magnetic tips suitable for switching magnetization MFM. Switching magnetization MFM is based on two-pass scanning atomic force microscopy with reversed tip magnetization between the scans. Within the technique the sum of the scanned data with reversed tip magnetization depicts local atomic forces, while their difference maps the local magnetic forces. Here we propose the design and calculate the magnetic properties of tips suitable for this scanning probe technique. We find that for best performance the spin-polarized tips must exhibit low magnetic moment, low switching fields, and single-domain state at remanence. The switching field of such tips is calculated and optimum shape of the Permalloy elements for the tips is found. We show excellent correspondence between calculated and experimental results for Py elements. 相似文献
12.
V. L. Mironov O. L. Ermolaeva 《Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques》2009,3(5):840-845
Optimal parameters for a data storage system based on ferromagnetic particles and magnetic force microscope (MFM) are calculated.
The conditions necessary for data recording, storing, and reading are analyzed in the frame of a simple model of a spherical
MFM probe and an array of spherical single-domain particles. The ultimate data densities in such a system are estimated. 相似文献
13.
Sena C Godinho MH Sebastião PJ Sousa D Neto FA 《The European physical journal. E, Soft matter》2011,34(1):8-11
We report on an experimental study of the structures presented by urethane/urea elastomeric films without and with ferromagnetic
nanoparticles incorporated. The study is made by using the X-ray diffraction, nuclear magnetic resonance (NMR), optical, atomic
and magnetic force (MFM) microscopy techniques, and mechanical assays. The structure of the elastomeric matrix is characterized
by a distance of 0.46nm between neighboring molecular segments, almost independent on the stretching applied. The shear casting
performed in order to obtain the elastomeric films tends to orient the molecules parallel to the flow direction thus introducing
anisotropy in the molecular network which is reflected on the values obtained for the orientational order parameter and its
increase for the stretched films. In the case of nanoparticles-doped samples, the structure remains nearly unchanged although
the local order parameter is clearly larger for the undoped films. NMR experiments evidence modifications in the molecular
network local ordering. Micrometer size clusters were observed by MFM for even small concentration of magnetic particles. 相似文献
14.
The ill-posed linear inverse problems, characterised by Fredholm integral equations of the first kind, are encountered in
many areas of science and technology. This type of problems present some loss of information under the inversion process.
The loss of information often makes the inversion process very difficult. Magnetic force microscopy (MFM) is a technique where
problems related to loss of information occur. Work is presented here to understand what can be measured by the magnetic force
microscope. A simple model is constructed, where the magnetic tip is approximated by a point dipole. Given the force F() acting on the dipole tip, we attempt to determine the magnetization distributlon in a thin ferromagnetic film, M(). This calculation should be interesting due to the rapidiy growing interest in magnetic thin films and magnetic multilayers.
Received 3 December 2001 and Received in final form 11 March 2002 相似文献
15.
16.
An algorithm for computer simulation of images obtained by magnetic force microscopy (MFM) is suggested. It is based on the Brown formalism and takes into account the shapes and the magnetic properties of the MFM tip and sample studied. The robustness and efficiency of the algorithm are tested by simulating the MFM image of a point magnetic dipole for the case where the tip is approximated by a nonmagnetic truncated cone covered by a thin uniformly magnetized layer. From the computer simulation of the MFM images of the dipole, the optimum parameters of the MFM probe are obtained. 相似文献
17.
J. Mohanty R. Engel-Herbert T. Hesjedal 《Applied Physics A: Materials Science & Processing》2005,81(7):1359-1362
Magnetic force microscopy (MFM) studies of epitaxial MnAs films on GaAs(001) have been performed as a function of the applied magnetic field and the sample temperature. For this purpose, we combined a stable variable-temperature sample stage with a compact magnet assembly to fit a commercial magnetic force microscope. In order to keep the thermal drift that affects MFM measurements low, we employed a permanent magnet that can be rotated in a yoke assembly guiding the magnetic flux to the sample. PACS 68.37.Rt; 68.35.Rh; 75.70.-i; 75.70.Kw 相似文献
18.
J. D. Wei I. Knittel C. Lang D. Schüler U. Hartmann 《Journal of nanoparticle research》2011,13(8):3345-3352
Biogenic magnetite nanoparticles (MNP) extracted from the magnetotactic bacterium Magnetospirillum gryphiswaldense MSR-1 have been systematically studied by atomic force microscopy (AFM) and magnetic force microscopy (MFM). Isolated single
MNP and chains of MNP were obtained from diluted MNP aqueous suspension dried on mica surfaces in a homogeneous in-plane magnetic
field. The size of the MNP was determined by employing AFM tip deconvolution procedures. The obtained result has been confirmed
by scanning electronic microscopy. Magnetic properties of isolated single MNP and chains of MNP in remanence and in the presence
of external magnetic fields were investigated by MFM. In particular, the magnetization reversal of a two-particle chain has
been revealed and the dipolar interaction between the MNP is estimated. The change in the magnetic contrast on application
of an external magnetic field is consistent with the hysteresis curve obtained by cantilever magnetometry. 相似文献
19.
Fe50Co50 thin films with thickness of 30 and 4 nm have been produced by rf sputtering on glass substrates, and their surface has been observed with atomic force microscopy (AFM) and magnetic force microscopy (MFM); MFM images reveal a non-null component of the magnetization perpendicular to the film plane. Selected samples have been annealed in vacuum at temperatures of 300 and 350 °C for times between 20 and 120 min, under a static magnetic field of 100 Oe. DC hysteresis loops have been measured with an alternating gradient force magnetometer (AGFM) along the direction of the field applied during annealing and orthogonally to it. Samples with a thickness of 4 nm display lower coercive fields with respect to the 30 nm thick ones. Longer annealing times affect the development of a harder magnetic phase more oriented off the film plane. The field applied during annealing induces a moderate magnetic anisotropy only on 30 nm thick films. 相似文献
20.
A. L. Brandl J. C. Denardin M. Knobel M. E. R. Dotto M. U. Kleinke 《Physica B: Condensed Matter》2002,320(1-4):213-216
A study of Co[SiO2] granular films using magnetic force microscopy (MFM), transmission electron microscopy and DC magnetization is presented. MFM shows large strip magnetic domains in the percolated system and allows a more direct investigation of the magnetic interaction among grains in the film with the lowest metal volume fraction. 相似文献