Magnetic domain structures and domain walls in iron fine particles

The high voltage Lorentz microscopy was successfully used to observe changes with temperature; of domain structures and metallurgical structures in an iron film set on the hot stage combined with a goniometer. The microscope used was the JEM-1000 EM which was operated with the objective lens current cut off to eliminate the magnetic field in the specimen position. Single crystal films with an (001) plane were prepared by the epitaxial growth of evaporated iron on a cleaved (001) plane of a rocksalt substrate. They had a uniform thickness from 1000 to 7000 Å.The figure shows the temperature dependence of magnetic domain structure with its corresponding deflection pattern and metallurgical structure observed in a 4500 Å iron film. In general, with increase of temperature, the straight domain walls decrease in their width (at 400°C), curve in an iregular shape (600°C) and then vanish (790°C). The ripple structures with cross-tie walls are observed below the Curie temperature.

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Atomic Structure-Sensitive Magnetic Domain Structures of Thin Films

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100117960 ◽

1985 ◽

Vol 43 ◽

pp. 206-209

Author(s):

S. Tsukahara

Keyword(s):

Thin Films ◽

Magnetic Properties ◽

Domain Walls ◽

Magnetic Domain ◽

Quarter Century ◽

Specimen Handling ◽

Lorentz Microscopy ◽

Domain Structures ◽

Structure Sensitive ◽

Direct Interpretation

Transmission electron microscopy, TEM, that can serve for observation of both atomic and magnetic structures is useful to investigate structure sensitive magnetic properties. It is most effective when it is applied to thin films for which direct interpretation of the results is possible without considering additional effects through specimen handling for TEM use and modification of dimension dependent magnetic properties.Transmission Lorentz microscopy, TLM, to observe magnetic domains has been known for a quarter century. Among TLM modes the defocused mode has been most popular due to its simple way of operation. Recent development of TEM made it possible that an average instrument commercially available could be easily operated at any TLM modes to produce high quality images. This paper mainly utilizes the Foucault mode to investigate domain walls and magnetization ripples as the finest details of domain structure.

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Clamped Ferroelectric and Magnetic Domain Walls and their Application to Memory Engineering

MRS Proceedings ◽

10.1557/proc-834-j6.4 ◽

2004 ◽

Vol 834 ◽

Author(s):

Eiichi Hanamura ◽

Yukito Tanabe

Keyword(s):

Domain Walls ◽

Second Harmonic ◽

Domain Boundary ◽

Magnetic Domain ◽

Earth Metal ◽

Weak Ferromagnetism ◽

Interference Effects ◽

Magnetic Anisotropy Energy ◽

Domain Structures ◽

Magnetic Domain Walls

ABSTRACTA family of rare-earth metal manganites are antiferromagnetic (AFM) ferroelectrics and some of these may show also weak ferromagnetism. First we will show how to observe the ferroelectric (FEL) and AFM domain structures by the interference effects of second harmonic generation (SHG). Second, the observed clamping of the AFM domain wall (DW) to the FEL domain boundary (DB) is intuitively explained by the group theoretical consideration of the magnetic anisotropy energy depending upon the sign of the FEL polarization. Third, the application of these clamped DW-DB to the memory engineering will be briefly discussed.

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Magnetization Reversal in Ferromagnetic Thin Films

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.399-401.890 ◽

2011 ◽

Vol 399-401 ◽

pp. 890-895

Author(s):

Jia Li Sun ◽

Jing Guo Hu

Keyword(s):

Magnetic Anisotropy ◽

Magnetization Reversal ◽

Domain Walls ◽

Magnetic Domain ◽

Ferromagnetic Film ◽

Magnetic Films ◽

Ferromagnetic Thin Films ◽

Interface Coupling ◽

Domain Structures ◽

Reversal Mechanism

The magnetization reversal mechanism of the magnetic films system with the different magnetic anisotropy, exchange coupling, interface coupling, etc. has been simulated by Monte-Carlo method. The results show that the decrease of magnetic anisotropy is in favor of motion of domain walls, but is not conducive to consistent rotation. The interface coupling of both the ferromagnetic film and the antiferromagnetic film are helpful to the motion of domain walls while the antiferromagnetic film coupling is the more effective. Meantime, the evolution of the microscopic magnetic domain structures has been inspected intuitively while the system is in the process of magnetization.

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On the Formation of High Damping State in Fe-Al and Fe-Cr Alloys

Solid State Phenomena ◽

10.4028/www.scientific.net/ssp.137.109 ◽

2008 ◽

Vol 137 ◽

pp. 109-118 ◽

Cited By ~ 1

Author(s):

I.B. Chudakov ◽

Nataly A. Polyakova ◽

S.Yu. Mackushev ◽

V.A. Udovenko

Keyword(s):

Domain Structure ◽

Domain Walls ◽

Volume Fraction ◽

Magnetic Domain ◽

Al Alloys ◽

The State ◽

Magnetic Domain Structure ◽

Damping Capacity ◽

Domain Structures ◽

Domain Boundaries

High damping Fe - Cr and Fe - Al alloys have been studied in two different states: in the high damping state and in the suppressed damping capacity state. It has been shown that magnetic domain structures of Fe - Cr and Fe - Al alloys are fundamentally different in the high damping state and in the state with the suppressed damping. Magnetic domain structure corresponding to the high damping state can be characterized by an enhanced volume fraction of the easy movable 90o-domain walls, but the state with the suppressed damping capacity can be characterized by the enhanced volume fraction of the 180o-domain boundaries.

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Resistance of single domain walls in half-metallic CrO2 epitaxial nanostructures

Nanoscale ◽

10.1039/d1nr05555k ◽

2021 ◽

Author(s):

Lijuan Qian ◽

Shiyu Zhou ◽

Kang Wang ◽

Gang Xiao

Keyword(s):

Electron Transport ◽

Domain Walls ◽

Magnetic Domain ◽

Single Domain ◽

Half Metallic ◽

Domain Structures ◽

Active Electron ◽

Excess Resistance

Magnetic domain structures are active electron transport agents and can be used to induce large magnetoresistance (MR), particularly in half-metallic solids. We have studied the excess resistance induced by a...

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Mutual control of coherent spin waves and magnetic domain walls in a magnonic device

Science ◽

10.1126/science.aau2610 ◽

2019 ◽

Vol 366 (6469) ◽

pp. 1121-1125 ◽

Cited By ~ 22

Author(s):

Jiahao Han ◽

Pengxiang Zhang ◽

Justin T. Hou ◽

Saima A. Siddiqui ◽

Luqiao Liu

Keyword(s):

Spin Wave ◽

Domain Walls ◽

Spin Waves ◽

Spin Current ◽

Magnetic Domain ◽

Spin Transfer Torque ◽

Successful Implementation ◽

Domain Structures ◽

Magnetic Domain Walls ◽

Coherent Spin

The successful implementation of spin-wave devices requires efficient modulation of spin-wave propagation. Using cobalt/nickel multilayer films, we experimentally demonstrate that nanometer-wide magnetic domain walls can be applied to manipulate the phase and magnitude of coherent spin waves in a nonvolatile manner. We further show that a spin wave can, in turn, be used to change the position of magnetic domain walls by means of the spin-transfer torque effect generated from magnon spin current. This mutual interaction between spin waves and magnetic domain walls opens up the possibility of realizing all-magnon spintronic devices, in which one spin-wave signal can be used to control others by reconfiguring magnetic domain structures.

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Magnetic Domain Structure of Hematite

Canadian Journal of Physics ◽

10.1139/p71-335 ◽

1971 ◽

Vol 49 (22) ◽

pp. 2768-2777 ◽

Cited By ~ 8

Author(s):

J. A. Eaton ◽

A. H. Morrish

Keyword(s):

Domain Structure ◽

Basal Plane ◽

Domain Walls ◽

Magnetic Domain ◽

Anisotropy Constant ◽

Wall Structure ◽

Strain Effect ◽

Two Phase ◽

Domain Structures ◽

Plane Anisotropy

Magnetic colloid observations on synthetic hematite indicate the existence of only two phase domain structures. The normal or N structure is a usually slablike 180° wall structure where the majority of walls are parallel to the basal plane and have a 100–200 μm separation. Wall energies are estimated to be 0.35 × 10−1 to 1.0 × 10−1 erg/cm2 from domain geometry. Under special circumstances, a domain structure, called CN domains, occurs in [Formula: see text] and [Formula: see text] surfaces and appears to be a two phase structure of non-180° walls. Spontaneous magnetostriction requires these walls of 100–200 μm separation to be planar and lie either perpendicular to or at ~26° to the basal plane. A third structure, called C domains, of 25–50 μm spaced planar walls occurs on (110) surfaces in two characteristic directions symmetric with the basal plane and consistent with CN-wall geometry. However, because of their behavior and geometry, they appear to be nonmagnetically stabilized but possibly by a strain effect. By using magnetoelastic coupling for the effective basal plane anisotropy constant for moment rotation in domain walls, N-wall energies are estimated to be 0.45 × 10−1 to 1.0 × 10−1 erg/cm2. Because of geometry complications CN-wall energies are difficult to calculate but are estimated to be ~10−1 erg/cm2 or slightly larger.

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The direct determination of magnetic domain wall profiles using a split detector STEM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100109471 ◽

1978 ◽

Vol 36 (1) ◽

pp. 466-467

Author(s):

J.N. Chapman ◽

P.E. Batson ◽

E.M. Waddell ◽

R.P. Ferrier

Keyword(s):

Electron Microscope ◽

Domain Wall ◽

Transmission Electron Microscope ◽

Domain Walls ◽

Photographic Plate ◽

Magnetic Domain ◽

Direct Determination ◽

Quantitative Information ◽

Scanning Transmission Electron Microscope ◽

Transmission Electron

By far the most commonly used mode of Lorentz microscopy in the examination of ferromagnetic thin films is the Fresnel or defocus mode. Use of this mode in the conventional transmission electron microscope (CTEM) is straightforward and immediately reveals the existence of all domain walls present. However, if such quantitative information as the domain wall profile is required, the technique suffers from several disadvantages. These include the inability to directly observe fine image detail on the viewing screen because of the stringent illumination coherence requirements, the difficulty of accurately translating part of a photographic plate into quantitative electron intensity data, and, perhaps most severe, the difficulty of interpreting this data. One solution to the first-named problem is to use a CTEM equipped with a field emission gun (FEG) (Inoue, Harada and Yamamoto 1977) whilst a second is to use the equivalent mode of image formation in a scanning transmission electron microscope (STEM) (Chapman, Batson, Waddell, Ferrier and Craven 1977), a technique which largely overcomes the second-named problem as well.

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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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