Electrically induced chiral magnetic domains in iron whiskers

In recent years, there has been increasing demand for higher voltage SEMs, in the field of surface observation, especially that of magnetic domains, dislocations, and electron channeling patterns by backscattered electron microscopy. On the other hand, the resolution of the CTEM has now reached 1 ∼ 2Å, and several reports have recently been made on the observation of atom images, indicating that the ultimate goal of morphological observation has beem nearly achieved.

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Lorentz microscopy study of magnetic domain walls in Fe-Cr-Co alloys

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100109458 ◽

1978 ◽

Vol 36 (1) ◽

pp. 462-463

Author(s):

Yalcin Belli

Keyword(s):

Domain Walls ◽

Magnetic Domain ◽

Microscopy Study ◽

Ferromagnetic Phase ◽

Stable Phase ◽

Magnetic Domains ◽

Lorentz Microscopy ◽

Magnetic Hardening ◽

Electron Microscopes ◽

Co Alloys

Fe-Cr-Co alloys have great technological potential to replace Alnico alloys as hard magnets. The relationship between the microstructures and the magnetic properties has been recently established for some of these alloys. The magnetic hardening has been attributed to the decomposition of the high temperature stable phase (α) into an elongated Fe-rich ferromagnetic phase (α1) and a weakly magnetic or non-magnetic Cr-rich phase (α2). The relationships between magnetic domains and domain walls and these different phases are yet to be understood. The TEM has been used to ascertain the mechanism of magnetic hardening for the first time in these alloys. The present paper describes the magnetic domain structure and the magnetization reversal processes in some of these multiphase materials. Microstructures to change properties resulting from, (i) isothermal aging, (ii) thermomagnetic treatment (TMT) and (iii) TMT + stepaging have been chosen for this investigation. The Jem-7A and Philips EM-301 transmission electron microscopes operating at 100 kV have been used for the Lorentz microscopy study of the magnetic domains and their interactions with the finely dispersed precipitate phases.

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Magnetic Material Observation Assembly for Tem with a Eucentric Goniometer

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100092669 ◽

1976 ◽

Vol 34 ◽

pp. 540-541

Author(s):

K. Shi rota ◽

A. Yonezawa ◽

K. Shibatomi ◽

T. Yanaka

Keyword(s):

Magnetic Material ◽

Electron Microscope ◽

Magnetic Domain ◽

Objective Lens ◽

Magnetic Domains ◽

Lorentz Microscopy ◽

Transmission Electron ◽

Correction Of Astigmatism ◽

Single Orientation ◽

Conventional Transmission Electron Microscope

As is well known, it is not so easy to operate a conventional transmission electron microscope for observation of magnetic materials. The reason is that the instrument requires re-alignment of the axis and re-correction of astigmatism after each specimen shift, as the lens field is greatly disturbed by the specimen. With a conventional electron microscope, furthermore, it is impossible to observe magnetic domains, because the specimen is magnetized to single orientation by the lens field. The above mentioned facts are due to the specimen usually being in the lens field. Thus, special techniques or systems are usually required for magnetic material observation (especially magnetic domain observation), for example, the technique to switch off the objective lens current and Lorentz microscopy. But these cannot give high image quality and wide magnification range, and furthermore Lorentz microscopy is very complicated.

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Lorentz electron microscopy of magnetic domains in rapidly solidified and annealed Pt-Co-B alloys

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100088233 ◽

1991 ◽

Vol 49 ◽

pp. 784-785

Author(s):

N. Qiu ◽

J. E. Wittig

Keyword(s):

Rapid Solidification ◽

Ion Beam ◽

Magnetic Behavior ◽

High Coercivity ◽

Magnetic Domains ◽

Beam Angle ◽

Tem Analysis ◽

Intrinsic Coercivity ◽

Hard Magnets ◽

Rapidly Solidified

PtCo hard magnets have specialized applications owing to their relatively high coercivity combined with corrosion resistance and ductility. Increased intrinsic coercivity has been recently obtained by rapid solidification processing of PtCo alloys containing boron. After rapid solidification by double anvil splat quenching and subsequent annealing for 30 minutes at 650°C, an alloy with composition Pt42Co45B13 (at.%) exhibited intrinsic coercivity up to 14kOe. This represents a significant improvement compared to the average coercivities in conventional binary PtCo alloys of 5 to 8 kOe.Rapidly solidified specimens of Pt42Co45B13 (at.%) were annealed at 650°C and 800°C for 30 minutes. The magnetic behavior was characterized by measuring the coercive force (Hc). Samples for TEM analysis were mechanically thinned to 100 μm, dimpled to about 30 nm, and ion milled to electron transparency in a Gatan Duomill at 5 kV and 1 mA gun current. The incident ion beam angle was set at 15° and the samples were liquid nitrogen cooled during milling. These samples were analyzed with a Philips CM20T TEM/STEM operated at 200 kV.

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Magnetic Domain Observation of an Amorphous Fe-Si-B Ribbon by Means of a High Voltage Scanning Electron Microscope

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100098113 ◽

1981 ◽

Vol 39 ◽

pp. 320-321

Author(s):

K. Tsuno ◽

Y. Harada ◽

T. Sato

Keyword(s):

Electron Microscope ◽

Scanning Electron Microscope ◽

High Voltage ◽

Amorphous Ribbon ◽

Image Resolution ◽

Objective Lens ◽

Magnetic Domains ◽

Scattered Electron ◽

Voltage Scanning ◽

Scanning Electron

Magnetic domains of ferromagnetic amorphous ribbon have been observed using Bitter powder method. However, the domains of amorphous ribbon are very complicated and the surface of ribbon is not flat, so that clear domain image has not been obtained. It has been desired to observe more clear image in order to analyze the domain structure of this zero magnetocrystalline anisotropy material. So, we tried to observe magnetic domains by means of a back-scattered electron mode of high voltage scanning electron microscope (HVSEM).HVSEM method has several advantages compared with the ordinary methods for observing domains: (1) high contrast (0.9, 1.5 and 5% at 50, 100 and 200 kV) (2) high penetration depth of electrons (0.2, 1.5 and 8 μm at 50, 100 and 200 kV). However, image resolution of previous HVSEM was quite low (maximum magnification was less than 100x), because the objective lens cannot be excited for avoiding the application of magnetic field on the specimen.

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The physics of magnetic domains

Uspekhi Fizicheskih Nauk ◽

10.3367/ufnr.0156.198809b.0047 ◽

1988 ◽

Vol 156 (9) ◽

pp. 47-92 ◽

Cited By ~ 36

Author(s):

V.G. Bar'yakhtar ◽

A.N. Bogdanov ◽

D.A. Yablonskii

Keyword(s):

Magnetic Domains

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Emergence of disconnected clusters in heterogeneous complex systems

Scientific Reports ◽

10.1038/s41598-020-78769-2 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

István A. Kovács ◽

Róbert Juhász

Keyword(s):

Complex Systems ◽

Percolation Theory ◽

Contact Process ◽

Heterogeneous Systems ◽

Critical Dynamics ◽

Magnetic Domains ◽

3 Dimensional ◽

Quantum Ising Model ◽

Highly Correlated ◽

Exact Renormalization Group

AbstractPercolation theory dictates an intuitive picture depicting correlated regions in complex systems as densely connected clusters. While this picture might be adequate at small scales and apart from criticality, we show that highly correlated sites in complex systems can be inherently disconnected. This finding indicates a counter-intuitive organization of dynamical correlations, where functional similarity decouples from physical connectivity. We illustrate the phenomenon on the example of the disordered contact process (DCP) of infection spreading in heterogeneous systems. We apply numerical simulations and an asymptotically exact renormalization group technique (SDRG) in 1, 2 and 3 dimensional systems as well as in two-dimensional lattices with long-ranged interactions. We conclude that the critical dynamics is well captured by mostly one, highly correlated, but spatially disconnected cluster. Our findings indicate that at criticality the relevant, simultaneously infected sites typically do not directly interact with each other. Due to the similarity of the SDRG equations, our results hold also for the critical behavior of the disordered quantum Ising model, leading to quantum correlated, yet spatially disconnected, magnetic domains.

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