scholarly journals Extreme anti-reflection enhanced magneto-optic Kerr effect microscopy

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Dongha Kim ◽  
Young-Wan Oh ◽  
Jong Uk Kim ◽  
Soogil Lee ◽  
Arthur Baucour ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Kerr Effect ◽  
Domain Walls ◽  
State Of The Art ◽  
Magnetic Domain ◽  
Diffraction Limit ◽  
Scanning Probe ◽  
Spintronic Devices ◽  
Sub Wavelength ◽  
Magneto Optic

AbstractMagnetic and spintronic media have offered fundamental scientific subjects and technological applications. Magneto-optic Kerr effect (MOKE) microscopy provides the most accessible platform to study the dynamics of spins, magnetic quasi-particles, and domain walls. However, in the research of nanoscale spin textures and state-of-the-art spintronic devices, optical techniques are generally restricted by the extremely weak magneto-optical activity and diffraction limit. Highly sophisticated, expensive electron microscopy and scanning probe methods thus have come to the forefront. Here, we show that extreme anti-reflection (EAR) dramatically improves the performance and functionality of MOKE microscopy. For 1-nm-thin Co film, we demonstrate a Kerr amplitude as large as 20° and magnetic domain imaging visibility of 0.47. Especially, EAR-enhanced MOKE microscopy enables real-time detection and statistical analysis of sub-wavelength magnetic domain reversals. Furthermore, we exploit enhanced magneto-optic birefringence and demonstrate analyser-free MOKE microscopy. The EAR technique is promising for optical investigations and applications of nanomagnetic systems.

Magneto-optic Kerr effect of domain walls in ferromagnetic double-layered films

1993 ◽  
Author(s):  
Ping Zhu ◽  
Zhong Xu ◽  
Yongshi Hu ◽  
Gengqi Lin ◽  
Zuoyi Lee
Keyword(s):  
Kerr Effect ◽  
Domain Walls ◽  
Magneto Optic

Lorentz electron microscopy of rare-earth permanent magnets

1983 ◽  
Vol 41 ◽  
pp. 254-255
Author(s):  
G. C. Hadjipanayis ◽  
L. L. Horton
Keyword(s):  
Electron Microscopy ◽  
Rare Earth ◽  
Permanent Magnets ◽  
Domain Walls ◽  
Defect Density ◽  
Hexagonal Phase ◽  
Magnetic Hysteresis ◽  
Magnetic Domain ◽  
Pole Piece ◽  
Two Phase

Rare-earth-cobalt permanent magnets are characterized by large coercive fields and energy products. The hard magnetic properties depend strongly on the microstructure and are usually achieved after a complex heat treatment. A single phase microstructure with low defect density has been observed in SmCo5 and Sm2Co17 magnets. The addition of copper to these materials produces a two-phase cellular structure with a 1:5 hexagonal phase at the cell boundaries and a 2:17 rhombohedral phase in the cell interiors. The single- and two-phase microstructures lead to different magnetic hysteresis behavior. The purpose of this work is to determine the relationship of the microstructure with the magnetic domain structure to further clarify the origin of the high-coercive fields in these permanent magnet materials. Lorentz electron microscopy has been used to image the domain walls and study their interactions with crystalline defects. A JEM 120C TEM equipped with an AMG objective pole piece has been used for these studies. The magnetic field at the specimen is 3.4 Oe with this pole piece.

Shadow and interference electron microscopy of magnetic domain walls

1978 ◽  
Vol 49 (2) ◽  
pp. K103-K107 ◽  
Author(s):  
S. Martelli ◽  
G. Matteucci ◽  
M. V. Antisari
Keyword(s):  
Electron Microscopy ◽  
Domain Walls ◽  
Magnetic Domain ◽  
Magnetic Domain Walls

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

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.

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

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.

Temperature Dependence of Magnetic Domains and Wall Structures

1972 ◽  
Vol 30 ◽  
pp. 496-497
Author(s):  
Sonoko Tsukahara ◽  
Tadami Taoka ◽  
Hisao Nishizawa
Keyword(s):  
Temperature Dependence ◽  
Domain Walls ◽  
Magnetic Domain ◽  
Iron Film ◽  
Objective Lens ◽  
Lorentz Microscopy ◽  
Domain Structures ◽  
Wall Structures ◽  
Crystal Films ◽  
Metallurgical Structure

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.

Sign in / Sign up

Export Citation Format

Share Document