scholarly journals Theory of nonlinear magneto-optical imaging of magnetic domains and domain walls

1997 ◽  
Vol 56 (5) ◽  
pp. 2680-2687 ◽  
Author(s):  
A. V. Petukhov ◽  
I. L. Lyubchanskii ◽  
Th. Rasing
Keyword(s):  
Optical Imaging ◽  
Domain Walls ◽  
Magnetic Domains

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.

scholarly journals Visualization of magnetostructural transition in Heusler alloys by Magnetic Force Microscopy

2018 ◽  
Vol 185 ◽  
pp. 05004
Author(s):  
Pavel Geydt ◽  
Igor D. Rodionov ◽  
Alexander B. Granovsky ◽  
Ekaterina Soboleva ◽  
Egor Fadeev ◽  
...  
Keyword(s):  
Magnetic Force Microscopy ◽  
Magnetic Force ◽  
Domain Walls ◽  
Heusler Alloys ◽  
Scanning Probe ◽  
Magnetic Domains ◽  
Magnetic Signal ◽  
Force Microscopy ◽  
Magnetostructural Transition ◽  
Probe Microscope

Magnetostructural transition was observed in Ni-Mn-In-Cr Heusler alloy with help of Magnetic Force Microscopy (MFM). The crystal structure of a sample and characteristic temperatures of the phase transition were controlled by roentgenostructural phase analysis and magnetometry, respectively. It appeared prominently important to prepare the surface of the sample until the nanometer level of surface roughness. Magnetic study performed with scanning probe microscope revealed existence of magnetic domains, which were spread across the surface evenly. Further studies revealed that intensity of magnetic signal decreases as fading out of the contrast of the MFM images. It was found that location of domains shifted after the heating/cooling cycle above Curie temperature for the studied alloy. Location of new domain walls appeared correlating with surface scrapings and defects, whilst it became independent from those after heating until just 70°C. The mechanism behind the observed transition is proposed.

scholarly journals In-Plane Magnetic Domains and Néel-like Domain Walls in Thin Flakes of the Room Temperature CrTe2 Van der Waals Ferromagnet

2020 ◽  
Vol 12 (27) ◽  
pp. 30702-30710 ◽  
Author(s):  
Anike Purbawati ◽  
Johann Coraux ◽  
Jan Vogel ◽  
Abdellali Hadj-Azzem ◽  
NianJheng Wu ◽  
...  
Keyword(s):  
Room Temperature ◽  
Domain Walls ◽  
Van Der Waals ◽  
Magnetic Domains

Behavior of Magnetic Domains in Single Magnetic Nanowire with Shallow Trench along Length Direction Observed by Magnetic Force Microscopy

2013 ◽  
Vol 1527 ◽  
Author(s):  
Mitsunobu Okuda ◽  
Yasuyoshi Miyamoto ◽  
Eiichi Miyashita ◽  
Naoto Hayashi
Keyword(s):  
Domain Walls ◽  
Hard Disk Drives ◽  
Magnetic Domain ◽  
Magnetic Memory ◽  
Magnetic Nanowires ◽  
Magnetic Domains ◽  
Electric Circuits ◽  
Recording Density ◽  
Magnetic Nanowire ◽  
Length Direction

ABSTRACTWe have proposed new magnetic memories using parallel-aligned nanowires without mechanical moving parts, in order to achieve the ultra high transfer rate of more than 144 Gbps for Super Hi-Vision TV. In the magnetic memory using nanowires, the data are stored as the magnetic domains with up or down magnetization in magnetic nanowires, and the domains are shifted quite faster by applying optimum current along the nanowire direction for data writing and reading purpose. Since the electric circuits and the insulation space between the neighbor nanowires are necessary for moving the magnetic domain walls, the areal recording density is essentially reduced as compared with that of conventional hard disk drives. In this study, in order to increase the areal recording density of magnetic nanowire memory, we have tried to act one magnetic nanowire as the virtual multiple data tracks. The shallow scratched trench was introduced using scanning probe microscopy along the length direction on the surface of a single nanowire to form multiple internal tracks, and we have succeeded in realizing a couple of virtual tracks states.

Magnetic Domains Observation from Bitter Patterns of NdFeB Alloy

2014 ◽  
Vol 802 ◽  
pp. 569-573 ◽  
Author(s):  
Raphael Lemos ◽  
Kaio Sérgio T. de Souza ◽  
Fernanda A. Sampaio da Silva ◽  
Daniel Rodrigues ◽  
José Adilson de Castro ◽  
...  
Keyword(s):  
Domain Walls ◽  
Cast Alloy ◽  
Colloid Solution ◽  
Magnetic Domains ◽  
Strong Anisotropy ◽  
Easy Magnetization ◽  
Domain Wall Energy ◽  
Magnetization Axis ◽  
Metallographic Preparation ◽  
Adequate Method

The Bitter method is an adequate method for domains observation, and depends on careful metallographic preparation and also on a proper magnetic colloid solution. In this study, Bitter patterns were obtained for a Nd-Fe-B as-cast alloy. The Nd2Fe14B grains show strong anisotropy during growing, and are larger for the direction perpendicular to the easy magnetization axis. The equilibrium distance between domain walls allows an estimate of intrinsic parameters of ferromagnetic phases as the domain wall energy and the single domain particle size.

Metal-insulator Transition and Magnetic Domains in (Ga,Mn)As Epilayers

2006 ◽  
Vol 941 ◽  
Author(s):  
Alexandre Dourlat ◽  
Catherine Gourdon ◽  
Vincent Jeudy ◽  
Frédéric Bernardot ◽  
Christophe Testelin ◽  
...  
Keyword(s):  
Domain Walls ◽  
Magnetic Domain ◽  
Perpendicular Magnetic Anisotropy ◽  
Domain Pattern ◽  
Magnetic Domains ◽  
Metal Insulator Transition ◽  
Metal Insulator ◽  
Large Size ◽  
Strong Pinning ◽  
Pinning Of Domain Walls

ABSTRACTWe investigate the magnetic domain pattern in (Ga,Mn)As epilayers with perpendicular magnetic anisotropy. We show that post-growth annealing, besides improving the magnetic and transport properties, also drastically changes the domain pattern. Strong pinning of domain walls along the <110> directions is suppressed and large-size domains are observed.

Lorentz Electron Microscopy of Magnetic Domains in Eptaxial Iron Films

1974 ◽  
Vol 32 ◽  
pp. 476-477
Author(s):  
K. R. Lawless ◽  
G. R. Proto
Keyword(s):  
Electron Microscopy ◽  
Single Crystal ◽  
Rock Salt ◽  
Domain Walls ◽  
Weak Field ◽  
Objective Lens ◽  
Magnetic Domains ◽  
Iron Films ◽  
Normal Operating ◽  
Iron Wire

This paper describes the results of a study of domain walls in single crystal iron films by Lorentz electron microscopy. The films were prepared by evaporating 99.99% iron wire onto an air cleaved (100) rock salt substrate heated to 400°C. The films were stripped from the rock salt, mounted on Cu folding grids and annealed at a temperature between 700°C and 900°C. The study was performed in a Siemens Elmiskop 1 A operated in the weak field objective lens mode with the specimen raised 5.4 mm. above its normal operating position.

Scanning electron microscopy with polarization analysis: An update

1991 ◽  
Vol 49 ◽  
pp. 764-765
Author(s):  
J. Unguris ◽  
M. W. Hart ◽  
R. J. Celotta ◽  
D. T. Pierce
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Domain Walls ◽  
Domain Wall Motion ◽  
Optical Recording ◽  
Polarization Analysis ◽  
Magnetic Domains ◽  
Magnetic Microstructure ◽  
Domain Structures ◽  
Scanning Electron

Over the past ten years the technique of scanning electron microscopy with polarization analysis (SEMPA) has rapidly evolved from a scientific curiosity to a useful analytical tool for looking at a material's magnetic microstructure. Several reviews of the technique have been published elsewhere. SEMPA has been successfully used to analyze various technological problems such as: noise in magnetic and magneto-optical recording media, domain wall motion in thin film recording heads, and domain structures in small Permalloy shapes. Basic science applications of SEMPA include quantitative studies of the influence of the surface on the structure of magnetic domains and domain walls, and studies of magnetic microstructures in ultra-thin (0.1 - 1 nm) ferromagnetic films. Many current applications of SEMPA make use of the technique's surface sensitivity to probe the magnetism of thin films and multilayers.

Mapping of Magnetic Domains by MFM in Ni2MnGa

2008 ◽  
Vol 52 ◽  
pp. 115-119 ◽  
Author(s):  
Deepti Jain ◽  
Soma Banik ◽  
L.S. Sharath Chandra ◽  
S.R. Barman ◽  
R. Nath ◽  
...  
Keyword(s):  
Domain Walls ◽  
Alloy System ◽  
Optical Microscope ◽  
Magnetic Domains ◽  
Local Magnetization ◽  
Force Microscopy ◽  
Domain Structures ◽  
Two Samples ◽  
Ferromagnetic Shape Memory ◽  
Curie Temperature Tc

Influence of structural transition in the evolution of the magnetic domains in the ferromagnetic shape memory alloy system Ni2+xMn1-xGa is reported here using Magnetic Force Microscopy (MFM) studies. Studies reported are with two samples with their martensite transition temperature TM less than and greater than the Curie temperature Tc. Present results show an evolution of MFM across the Tc with a clear twin domains and sub domain structures inside the twins. The higher spatial resolution of MFM (~50nm) as compared to optical microscope (400nm) is useful in probing the domain walls. Force derivative of the MFM signal that may be used as an order parameter seems to scale the onset of magnetic order in the system. One can clearly see the vanishing of the MFM patterns for T>Tc. Results are discussed in the light of models available for tip-sample interactions that track the local magnetization.

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