Observation of magnetic structures under external fields by the photothermally modulated stray field technique

In the last decade since its development, magnetic force microscopy[l] has emerged as a workhorse in imaging magnetic structures at the sub-micron length scales. It possesses the desirable attributes of robustness, straightforward implementation and a fairly well characterized image contrast formation. In recent years, we have successfully implemented MFM in the presence of a highly controlled external magnetic field.[2] Using this technique, it is possible to follow the sample’s magnetic evolution at various points along it’s magnetization curve. Further, by using standard software implementation, the images can be presented as an animation of the micromagnetic process. We applied this technique to study a variety of slow varying dynamics of magnetic systems, including the dc erasure of thin film recording media[3], the mechanisms of moment rotation and reversal, and the domain wall motion nanostructured magnetic elements[4,5].In this talk, I will review the rudiments of the technique and show the “dynamics” of the magnetization of cobalt and Permalloy alloys interacting with external fields.

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Magnetic force microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100088154 ◽

1991 ◽

Vol 49 ◽

pp. 768-769

Author(s):

P. Grütter ◽

D. Rugar ◽

H.-J. Mamin ◽

T.R. Albrecht

Keyword(s):

Magnetic Force Microscopy ◽

Magnetic Force ◽

Central Component ◽

Stray Field ◽

Short Introduction ◽

Present Measurement ◽

Cantilever Deflection ◽

Magnetic Structures ◽

Force Microscopy ◽

Non Destructive

The aim of this talk is to give a short introduction to the technique of magnetic force microscopy (MFM), review recent advances in instrumentation and present measurement on various magnetic materials.MFM [1, 2] is a non-destructive method which allows the imaging of magnetic structures with little or no sample preparation on a 50-100 nm scale. The central component of every MFM is a sharp magnetic tip mounted on a flexible cantilever. The interaction of the magnetic tip with a sample stray field leads to a change of both cantilever deflection and resonant frequency. These changes are measured with a sensitive displacement probe, eg. an interferometer. Images are generated by raster scanning the sample relative to the tip and recording the tip-sample interaction as a function of position.

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Pressure effects of the magnetic structures of TbNi2Si2 in external fields

Physica B Condensed Matter ◽

10.1016/s0921-4526(97)00683-2 ◽

1997 ◽

Vol 241-243 ◽

pp. 657-659 ◽

Cited By ~ 1

Author(s):

S Kawano ◽

A Moriai ◽

A Ohtomo ◽

A Onodera ◽

F Amita ◽

...

Keyword(s):

Pressure Effects ◽

External Fields ◽

Magnetic Structures

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Contrast of Filament Bright Rims

International Astronomical Union Colloquium ◽

10.1017/s0252921100025628 ◽

1994 ◽

Vol 144 ◽

pp. 365-367

Author(s):

E. V. Kononovich ◽

O. B. Smirnova ◽

P. Heinzel ◽

P. Kotrč

Keyword(s):

High Altitude ◽

Line Profile ◽

Line Center ◽

Magnetic Structures ◽

The Mean

AbstractThe Hα filtergrams obtained at Tjan-Shan High Altitude Observatory near Alma-Ata (Moscow University Station) were measured in order to specify the bright rims contrast at different points along the line profile (0.0; ± 0.25; ± 0.5; ± 0.75 and ± 1.0 Å). The mean contrast value in the line center is about 25 percent. The bright rims interpretation as the bases of magnetic structures supporting the filaments is suggested.

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Dislocations, Ordering and Antiferromagnetic Domains in MnO

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100069600 ◽

1970 ◽

Vol 28 ◽

pp. 522-523

Author(s):

D. J. Barber ◽

R. G. Evans

Keyword(s):

Electron Diffraction ◽

Single Crystal ◽

Optical Microscopy ◽

Defect Chemistry ◽

Magnetic Structures ◽

Optically Transparent ◽

Magnetic Features ◽

Antiferromagnetic Domains

Manganese (II) oxide, MnO, in common with CoO, NiO and FeO, possesses the NaCl structure and shows antiferromagnetism below its Neel point, Tn∼ 122 K. However, the defect chemistry of the four oxides is different and the magnetic structures are not identical. The non-stoichiometry in MnO2 small (∼2%) and below the Tn the spins lie in (111) planes. Previous work reported observations of magnetic features in CoO and NiO. The aim of our work was to find explanations for certain resonance results on antiferromagnetic MnO.Foils of single crystal MnO were prepared from shaped discs by dissolution in a mixture of HCl and HNO3. Optical microscopy revealed that the etch-pitted foils contained cruciform-shaped precipitates, often thick and proud of the surface but red-colored when optically transparent (MnO is green). Electron diffraction and probe microanalysis indicated that the precipitates were Mn2O3, in contrast with recent findings of Co3O4 in CoO.

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A Many-Beam Technique for Enhanced Resolution of Partial Dislocations

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100096485 ◽

1972 ◽

Vol 30 ◽

pp. 646-647

Author(s):

J. M. Oblak ◽

B. H. Kear

Keyword(s):

Phase Shift ◽

Field Method ◽

Dark Field ◽

Bright Field ◽

Field Technique ◽

Weak Beam ◽

Partial Dislocations ◽

Enhanced Resolution ◽

Nickel Base ◽

Beam Technique

The “weak-beam” and systematic many-beam techniques are the currently available methods for resolution of closely spaced dislocations or other inhomogeneities imaged through strain contrast. The former is a dark field technique and image intensities are usually very weak. The latter is a bright field technique, but generally use of a high voltage instrument is required. In what follows a bright field method for obtaining enhanced resolution of partial dislocations at 100 KV accelerating potential will be described.A brief discussion of an application will first be given. A study of intermediate temperature creep processes in commercial nickel-base alloys strengthened by the Ll2 Ni3 Al γ precipitate has suggested that partial dislocations such as those labelled 1 and 2 in Fig. 1(a) are in reality composed of two closely spaced a/6 <112> Shockley partials. Stacking fault contrast, when present, tends to obscure resolution of the partials; thus, conditions for resolution must be chosen such that the phase shift at the fault is 0 or a multiple of 2π.

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