Structure and Sensor Properties of a Robust GMR Material System

1999 ◽  
Vol 562 ◽  
Author(s):  
K.-M. H. Lenssen ◽  
J. J. T. M. Donkers ◽  
A. E. T. Kuiper ◽  
J. VAN Driel
Keyword(s):  
Magnetic Field ◽  
Blocking Temperature ◽  
Material Structure ◽  
Material System ◽  
Direct Effects ◽  
Strong Magnetic Fields ◽  
Exchange Biasing ◽  
Transmission Electron ◽  
Sensor Properties ◽  
The Right

ABSTRACTRecently we have developed a robust GMR material system, based on an artificial antiferromagnet which is exchange-biased with Ir-Mn. By combining magnetoresistance and magnetization measurements with Transmission Electron Microscopy analyses we show that the degree of [111] texture has direct effects on the sensor properties of the GMR multilayer. The degree of texture turns out to depend not only on the buffer layer, but also on the thickness of the Ir-Mn layer. The strongest texture is found for Ir-Mn layer thicknesses of around 4 nm. For this thickness the largest exchange-biasing field and GMR ratio are also obtained (after cooling in a magnetic field), but the blocking temperature is significantly reduced. If attention is paid to the material structure by choosing the right materials, layer thicknesses and stack order, a robust GMR multilayer system can be made that can withstand high temperatures (> 200°C) and strong magnetic fields (> 200 kA/m), as has been demonstrated experimentally.

scholarly journals Magnetic Properties and AC Losses in AFe2O4(A = Mn, Co, Ni, Zn) Nanoparticles Synthesized from Nonaqueous Solution

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Oleksandr Yelenich ◽  
Sergii Solopan ◽  
Taras Kolodiazhnyi ◽  
Yuliya Tykhonenko ◽  
Alexandr Tovstolytkin ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Measurements ◽  
Spinel Ferrite ◽  
Blocking Temperature ◽  
Ac Losses ◽  
X Ray Diffraction ◽  
Average Magnetic Moment ◽  
Heating Efficiency ◽  
Cobalt Nickel ◽  
Transmission Electron

Nanosized particles of AFe2O4(A = Mn, Co, Ni, or Zn) spinel ferrites were synthesized by coprecipitation from nonaqueous solutions using nitrate salts as starting reagents. The particles were characterized by X-ray diffraction, transmission electron microscopy, and magnetic measurements. Quasistatic magnetic measurements show superparamagnetic behavior with blocking temperature below room temperature for cobalt, nickel, and zinc spinel ferrite nanoparticles. Characteristic magnetic parameters of the particles including average magnetic moment of an individual nanoparticle and blocking temperature have been determined. The specific loss power which is released on the exposure of an ensemble of synthesized particles to a magnetic field is calculated and measured experimentally. It is shown that among all nanoferrites under study, the ZnFe2O4nanoparticles demonstrate the highest heating efficiency in AC magnetic fields. The key parameters responsible for the heating efficiency in AC magnetic field have been determined. The directions to enhance the SLP value have been outlined.

Ion thinning of integrated circuit transverse specimens for transmission electron microscopy

1992 ◽  
Vol 50 (2) ◽  
pp. 1426-1427
Author(s):  
F. Shaapur
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Integrated Circuit ◽  
Substrate Surface ◽  
Homogeneous Material ◽  
Material System ◽  
Ion Milling ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Motion Profile

Non-uniform ion-thinning of heterogenous material structures has constituted a fundamental difficulty in preparation of specimens for transmission electron microscopy (TEM). A variety of corrective procedures have been developed and reported for reducing or eliminating the effect. Some of these techniques are applicable to any non-homogeneous material system and others only to unidirectionalfy heterogeneous samples. Recently, a procedure of the latter type has been developed which is mainly based on a new motion profile for the specimen rotation during ion-milling. This motion profile consists of reversing partial revolutions (RPR) within a fixed sector which is centered around a direction perpendicular to the specimen heterogeneity axis. The ion-milling results obtained through this technique, as studied on a number of thin film cross-sectional TEM (XTEM) specimens, have proved to be superior to those produced via other procedures.XTEM specimens from integrated circuit (IC) devices essentially form a complex unidirectional nonhomogeneous structure. The presence of a variety of mostly lateral features at different levels along the substrate surface (consisting of conductors, semiconductors, and insulators) generally cause non-uniform results if ion-thinned conventionally.

Application of electron holography to material science studies on magnetic domain states of small particles

1993 ◽  
Vol 51 ◽  
pp. 1028-1029
Author(s):  
T. Hirayama ◽  
Q. Ru ◽  
T. Tanji ◽  
A. Tonomura
Keyword(s):  
Magnetic Field ◽  
Material Science ◽  
Science Studies ◽  
Phase Distribution ◽  
Carbon Film ◽  
Objective Lens ◽  
Electron Holography ◽  
Transform Method ◽  
Transmission Electron ◽  
Thin Carbon

The observation of small magnetic materials is one of the most important applications of electron holography to material science, because interferometry by means of electron holography can directly visualize magnetic flux lines in a very small area. To observe magnetic structures by transmission electron microscopy it is important to control the magnetic field applied to the specimen in order to prevent it from changing its magnetic state. The easiest method is tuming off the objective lens current and focusing with the first intermediate lens. The other method is using a low magnetic-field lens, where the specimen is set above the lens gap.Figure 1 shows an interference micrograph of an isolated particle of barium ferrite on a thin carbon film observed from approximately [111]. A hologram of this particle was recorded by the transmission electron microscope, Hitachi HF-2000, equipped with an electron biprism. The phase distribution of the object electron wave was reconstructed digitally by the Fourier transform method and converted to the interference micrograph Fig 1.

scholarly journals The measurement of the energy of cosmic rays - II—The curvature measurements and the energy spectrum

1936 ◽  
Vol 154 (883) ◽  
pp. 573-587 ◽  
Keyword(s):  
Magnetic Field ◽  
Energy Spectrum ◽  
Cosmic Rays ◽  
Magnetic Fields ◽  
Strong Magnetic Fields ◽  
The Earth ◽  
Primary Particles ◽  
Curvature Measurements

Both the penetrating power of the cosmic rays through material ab­sorbers and their ability to reach the earth in spite of its magnetic field, make it certain that the energy of many of the primary particles must reach at least 10 11 e-volts. However, the energy measurements by Kunze, and by Anderson, using cloud chambers in strong magnetic fields, have extended only to about 5 x 10 9 e-volts. Particles of greater energy were reported, but the curvature of their tracks was too small to be measured with certainty. We have extended these energy measurements to somewhat higher energies, using a large electro-magnet specially built for the purpose and described in Part I. As used in these experiments, the magnet allowed the photography of tracks 17 cm long in a field of about 14,000 gauss. The magnet weighed about 11,000 kilos and used a power of 25 kilowatts.

scholarly journals Null Effect of Transcranial Static Magnetic Field Stimulation over the Dorsolateral Prefrontal Cortex on Behavioral Performance in a Go/NoGo Task

2021 ◽  
Vol 11 (4) ◽  
pp. 483
Author(s):  
Tatsunori Watanabe ◽  
Nami Kubo ◽  
Xiaoxiao Chen ◽  
Keisuke Yunoki ◽  
Takuya Matsumoto ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Prefrontal Cortex ◽  
Inhibitory Control ◽  
Static Magnetic Field ◽  
Dorsolateral Prefrontal Cortex ◽  
Cortical Excitability ◽  
Control Function ◽  
Field Stimulation ◽  
Dorsolateral Prefrontal ◽  
The Right

The purpose of this pilot study was to investigate whether transcranial static magnetic field stimulation (tSMS), which can modulate cortical excitability, would influence inhibitory control function when applied over the dorsolateral prefrontal cortex (DLPFC). Young healthy adults (n = 8, mean age ± SD = 24.4 ± 4.1, six females) received the following stimulations for 30 min on different days: (1) tSMS over the left DLPFC, (2) tSMS over the right DLPFC, and (3) sham stimulation over either the left or right DLPFC. The participants performed a Go/NoGo task before, immediately after, and 10 min after the stimulation. They were instructed to extend the right wrist in response to target stimuli. We recorded the electromyogram from the right wrist extensor muscles and analyzed erroneous responses (false alarm and missed target detection) and reaction times. As a result, 50% of the participants made erroneous responses, and there were five erroneous responses in total (0.003%). A series of statistical analyses revealed that tSMS did not affect the reaction time. These preliminary findings suggest the possibility that tSMS over the DLPFC is incapable of modulating inhibitory control and/or that the cognitive load imposed in this study was insufficient to detect the effect.

Direct Effects of Dopamine, Orciprenaline and Norepinephrine on the Right and Left Ventricle of Isolated Canine Hearts

Cardiology ◽  
1979 ◽  
Vol 64 (3) ◽  
pp. 133-148 ◽  
Author(s):  
H.D. Schmidt ◽  
H. Hoppe ◽  
L. Heidenreich
Keyword(s):  
Left Ventricle ◽  
Direct Effects ◽  
The Right

Fabrication and characterization of highly textured (Bi,Pb)2Sr2Ca2Cu3Ox superconducting ceramics using high magnetic field and cold isostatic pressing

1995 ◽  
Vol 10 (10) ◽  
pp. 2433-2443 ◽  
Author(s):  
Wai Lo ◽  
R. Stevens ◽  
R. Doyle ◽  
A.M. Campbell ◽  
W.Y. Liang
Keyword(s):  
Magnetic Field ◽  
Electron Microscopy ◽  
Cold Isostatic Pressing ◽  
Sintered Ceramic ◽  
Grain Alignment ◽  
Isostatic Pressing ◽  
Transmission Electron ◽  
Superconducting Ceramics ◽  
High Degree

High textured (Bi,Pb)2Sr2Ca2Cu3Ox ceramics have been fabricated by aligning deflocculated flakes of (Bi,Pb)2Sr2Ca2Cu3Ox suspended in an organic medium by means of a high de magnetic field (6 T) at room temperature followed by cold isostatic pressing. The proportion of the (Bi,Pb)2Sr2Ca2Cu3Ox phase in the precursor powder was carefully controlled, and the characteristics of the powder, such as size distribution and morphology, were determined. A high degree of grain alignment was found in the specimens after the magnetic alignment, although the bulk density of the materials was low. Cold isostatic pressing substantially increased the density of the magnetically prealigned specimens which also resulted in a slight decrease in the degree of grain alignment. This minor realignment was found to be due to the various kinds of processing defects that appeared in the specimens during compaction due to the grinding and cracking of the grains and their interlocking. The microstructural and superconducting properties of the sintered ceramic have been studied using texture goniometry, high resolution scanning electron microscopy, transmission electron microscopy, ac magnetic susceptometry, and critical current measurements.

Morphometric analysis of the actions of angiotensin II on renal arterioles and glomeruli

1992 ◽  
Vol 262 (3) ◽  
pp. F367-F372 ◽  
Author(s):  
K. M. Denton ◽  
P. A. Fennessy ◽  
D. Alcorn ◽  
W. P. Anderson
Keyword(s):  
Electron Microscopy ◽  
Angiotensin Ii ◽  
Vascular Resistance ◽  
Morphometric Analysis ◽  
Unit Length ◽  
Average Difference ◽  
Outer Cortex ◽  
Efferent Arteriole ◽  
Transmission Electron ◽  
The Right

To study the effects of angiotensin II on afferent and efferent arteriole diameters and on intraglomerular dimensions, angiotensin II (20 ng.kg-1.min-1) or saline vehicle was infused intravenously for 20 min into anesthetized rabbits pretreated with enalapril. Both kidneys were perfusion fixed (glutaraldehyde), and vascular casts were made of the right kidneys using methacrylate. Morphometric analysis of the left kidneys using transmission electron microscopy revealed no significant effects of angiotensin II within the glomerulus, including the degree of mesangial contraction. The diameters of the afferent and efferent arteriole casts from the right kidneys were measured at 20, 50, and 75 microns from the glomerulus by scanning electron microscopy. In the outer cortex the mean diameters of the afferent and efferent arterioles were 14.1 +/- 0.8 and 9.7 +/- 0.5 microns, respectively, in the angiotensin II-infused rabbits, significantly less than in the control (vehicle) rabbits, 17.0 +/- 0.7 microns (P less than 0.001) and 10.7 +/- 0.4 microns (P less than 0.005), respectively. Calculation of the relative changes in vascular resistance, however, indicated that the effects of angiotensin II on efferent arteriole resistance (average difference 2.4 +/- 1.2 units/microns) were significantly greater per unit length than the effects on afferent arteriole resistance (average difference 0.9 +/- 0.3 units/microns). Thus infused angiotensin II caused greater reduction in afferent arteriolar diameter than in efferent, but the calculated increase in vascular resistance per micron was greater in efferent vessels due to their smaller resting diameter.

scholarly journals INFLUENCE OF MATERIAL STRUCTURE ON THE MAGNETOSTRICTIVE PROPERTIES OF A RADIATOR FOR DEFROSTING HEAT EXCHANGERS OF VENTILATION EQUIPMENT

2021 ◽  
Vol 4 (4) ◽  
pp. 5-10
Author(s):  
T. Il'ina ◽  
P. Orlov ◽  
A. Chizhov
Keyword(s):  
Magnetic Field ◽  
Heat Exchanger ◽  
External Magnetic Field ◽  
Boiling Point ◽  
Heat Exchangers ◽  
Material Structure ◽  
Moist Air ◽  
Mechanical Vibrations ◽  
Suitable Material

the article deals with the properties of ferromagnetics and their behaviour in an external magnetic field. The conditions under which magnetism occurs in materials are shown and the choice of material for a magneto-strictive emitter is justified. The composition and properties of permendur as the most suitable material for the manufacture of magnetostrictive radiators are presented. It is shown that for the manufacture of the magnetostrictor it is feasible to use electro-erosion equipment for cutting packages from permendur com-pared to the costly and cumbersome method of stamping in a matrix of a particular shape. Tests were carried out on a duralumin heat exchanger with artificial frostbite. The evaporator was fed with refrigerant at 0.22 MPa, which corresponds to the boiling point of R 410a refrigerant at 35°C, by means of a refrigerant line made of aluminium pipes. Frostbite was then produced by applying moist air using an ultrasonic steam gen-erator. Frost on the evaporator surface is discharged by means of a magnetostrictor mounted on the heat ex-changer. The proposed method allows for the most effective cleaning of the surfaces of heat exchangers of ventilation equipment from scale, fouling and other mechanical deposits by means of mechanical vibrations.

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