scholarly journals Effect of a Dc Oblique Magnetic Field on the Magnetic Susceptibility of the Super-Paramagnetics Nanoparticles in Very Low Damping

2020 ◽  
pp. 1-3
Author(s):  
Malika MADANI ◽  
◽  
Bachir OUARI ◽  
Keyword(s):  
Magnetic Susceptibility ◽  
Magnetic Fields ◽  
Transverse Relaxation ◽  
Damping Parameter ◽  
Complex Susceptibility ◽  
Relaxation Modes ◽  
Oblique Field ◽  
Arbitrary Amplitude ◽  
Matrix Continued Fraction ◽  
Oblique Magnetic Field

The Magnetic Susceptibility of an individual Super-Paramagnetic nanoparticle in a presence of DC Oblique magnetic fields of arbitrary amplitude is investigated using Brown’s continuous diffusion model. The susceptibility is calculated and compared when for extensive ranges of the anisotropy, the dc magnetic fields in the very low damping with Matrix continued Fraction. It is shown that the shape of the Spectrum of Super-Paramagnetic nanoparticles is substantially altered by applying a dc oblique field. There is also an inherent geometric dependence of the complex susceptibility on the damping parameter arising from coupling of longitudinal and transverse relaxation modes

Magnetic susceptibility of an organosilicon based magnetic fluid in electric and magnetic fields

2015 ◽  
Vol 41 (2) ◽  
pp. 200-202
Author(s):  
Yu. I. Dikanskii ◽  
D. V. Gladkikh ◽  
S. A. Kunikin ◽  
A. V. Radionov
Keyword(s):  
Magnetic Susceptibility ◽  
Magnetic Fields ◽  
Magnetic Fluid ◽  
Electric And Magnetic Fields

scholarly journals Magnetic susceptibility imaging of human habenula at 3 T

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Seulki Yoo ◽  
Joo-won Kim ◽  
John F. Schenck ◽  
Seung-Kyun Lee
Keyword(s):  
Magnetic Susceptibility ◽  
High Resolution ◽  
Transverse Relaxation Rate ◽  
Transverse Relaxation ◽  
Reward Circuitry ◽  
High Prevalence ◽  
Psychiatric Conditions ◽  
Susceptibility Contrast ◽  
Deep Brain

Abstract The habenula plays an important role in brain reward circuitry and psychiatric conditions. While much work has been done on the function and structure of the habenula in animal models, in vivo imaging studies of the human habenula have been relatively scarce due to its small size, deep brain location, and lack of clear biomarkers for its heterogeneous substructure. In this paper, we report high-resolution (0.5 × 0.5 × 0.8 mm3) MRI of the human habenula with quantitative susceptibility mapping (QSM) at 3 T. By analyzing 48 scan datasets collected from 21 healthy subjects, we found that magnetic susceptibility contrast is highly non-uniform within the habenula and across the subjects. In particular, we observed high prevalence of elevated susceptibility in the posterior subregion of the habenula. Correlation analysis between the susceptibility and the effective transverse relaxation rate (R2*) indicated that localized susceptibility enhancement in the habenula is more associated with increased paramagnetic (such as iron) rather than decreased diamagnetic (such as myelin) sources. Our results suggest that high-resolution QSM could make a potentially useful tool for substructure-resolved in vivo habenula imaging, and provide a groundwork for the future development of magnetic susceptibility as a quantitative biomarker for human habenula studies.

A variational calculation of magnetized correlated fermion system using a spin-dependent correlation: Application to liquid 3He

2015 ◽  
Vol 29 (07) ◽  
pp. 1550046 ◽  
Author(s):  
Gholam Hossein Bordbar ◽  
Mohammad Taghi Mohammadi Sabet
Keyword(s):  
Magnetic Field ◽  
Magnetic Susceptibility ◽  
Correlation Function ◽  
Magnetic Fields ◽  
Spin Correlation ◽  
Variational Calculation ◽  
Fermion System ◽  
Magnetic Instability ◽  
Spin Correlation Function ◽  
Dependent Correlation

In the presence of magnetic field, we have employed a spin-dependent correlation function to investigate the properties of liquid 3 He using the variational method based on the cluster expansion of the energy. It has been indicated that at all relevant magnetic fields and densities, the inclusion of spin-dependency for the correlation function leads to the lower magnitudes for the kinetic, magnetic and potential energies, and therefore the total energy of this system. We have seen that the spin–spin correlation affects the system to be less magnetized compared to the case in which we consider the spin-independent correlation, especially at low densities. In the case of spin–spin correlation function, our results show a maximum in the magnetic susceptibility, and therefore a meta-magnetic instability for the system for the magnetic fields in the range 50 T ≤ B ≤ 60 T . This behavior has not been observed in the case of spin-independent correlation.

scholarly journals Effect of the Damping on the Magnetization of Antiferromagnetic Nanoparticles in a Presence of an Oblique Magnetic Field

2021 ◽  
pp. 1-7
Author(s):  
Bachir Ouari ◽  
◽  
Malika Madani ◽  
Mohamed Lagraa ◽  
◽  
...  
Keyword(s):  
Magnetic Field ◽  
Distribution Function ◽  
Relaxation Times ◽  
Planck Equation ◽  
Dynamic Susceptibility ◽  
Analytic Equation ◽  
Fokker Planck Equation ◽  
Oblique Field ◽  
Oblique Magnetic Field ◽  
Fokker Planck

The magnetization of antiferromagnetic nanoparticles is investigated with the Fokker-Planck equation describing the evolution of the distribution function of the magnetization of an nanoparticle. By solving this equation numerically, the relaxation times, and dynamic susceptibility are calculated for dc field orientations across wide ranges of frequencies, amplitude of the fields and damping. Analytic equation for the dynamic susceptibility is also proposed. It is shown that the damping alters the magnetization in the presence of oblique field applied

scholarly journals The study of the magnetic properties of matter strong magnetic fields.—I.—The balance and its properties

1931 ◽  
Vol 131 (816) ◽  
pp. 224-243 ◽  
Keyword(s):  
Magnetic Susceptibility ◽  
Magnetic Fields ◽  
Room Temperature ◽  
Direct Method ◽  
Magnetic Moments ◽  
Zeeman Effect ◽  
Inhomogeneous Magnetic Field ◽  
Present Communication ◽  
Strong Magnetic Fields ◽  
Short Times

In several previous communications the author has described a method by which magnetic fields up to 300,000 gauss could be obtained for a duration of time of the order of 1/100 of a second. It was shown that these magnetic fields, in spite of the shortness of their duration, can be applied to the study of different phenomena such as the change of resistance, the Zeeman effect, and others. The present paper describes a number of investigations which have been made on different substances, extending the application of intense magnetic fields to the study of magnetic susceptibility and magnetostriction. The interest in measuring the susceptibility of different substances in strong magnetic fields lies mainly in seeing whether the linear law of magnetisation for ordinary para- and diamagnetic substances holds for higher fields, and also in the investigation of the saturation of paramagnetic bodies at low temperatures, with a view to determining the elementary magnetic moments. In the present communication a method of measuring the magnetic susceptibility is described and experimental results are given which verify the linear law of magnetisation for several paramagnetic and diamagnetic substances. The saturation of iron and nickel in strong fields is also studied. As will be seen later, the possibility of making these measurements in such a small fraction of time results from the increased magnitude of the phenomenon itself. The most direct method for measuring the magnetic susceptibility is to record the force on a magnetised body in an inhomogeneous magnetic field. In the usual experiments at room temperature this force is only a few hundred dynes, but when fields reach the magnitude of 300 kilogauss the force becomes several grams, and is then sufficiently large to be measured with fair accuracy even in short times of the order of 1/100 of a second. In this paper a special type of balance will be described by which these measurements are made possible.

Magnetic phenomena

2004 ◽  
Author(s):  
Robert E. Newnham
Keyword(s):  
Magnetic Field ◽  
Magnetic Properties ◽  
Magnetic Susceptibility ◽  
Magnetic Fields ◽  
Magnetic Flux ◽  
Flux Density ◽  
Magnetic Dipole ◽  
Electric Charge ◽  
Dipole Moments ◽  
Magnetic Flux Density

In this chapter we deal with a number of magnetic properties and their directional dependence: pyromagnetism, magnetic susceptibility, magnetoelectricity, and piezomagnetism. In the course of dealing with these properties, two new ideas are introduced: magnetic symmetry and axial tensors. Moving electric charge generates magnetic fields and magnetization. Macroscopically, an electric current i flowing in a coil of n turns per meter produces a magnetic field H = ni amperes/meter [A/m]. On the atomic scale, magnetization arises from unpaired electron spins and unbalanced electronic orbital motion. The weber [Wb] is the basic unit of magnetic charge m. The force between two magnetic charges m1 and m2 is where r is the separation distance and μ0 (=4π×10−7 H/m) is the permeability of vacuum. In a magnetic field H, magnetic charge experiences a force F = mH [N]. North and south poles (magnetic charges) separated by a distance r create magnetic dipole moments mr [Wb m]. Magnetic dipole moments provide a convenient way of picturing the atomistic origins arising from moving electric charge. Magnetization (I) is the magnetic dipole moment per unit volume and is expressed in units of Wb m/m3 = Wb/m2. The magnetic flux density (B = I + μ0H) is also in Wb/m2 and is analogous to the electric displacement D. All materials respond to magnetic fields, producing a magnetization I = χH, and a magnetic flux density B = μH where χ is the magnetic susceptibility and μ is the magnetic permeability. Both χ and μ are in henries/m (H/m). The permeability μ = χ + μ0 and is analogous to electric permittivity. χ and μ are sometimes expressed as dimensionless quantities (x ̅ and μ ̅ and ) like the dielectric constant, where = x ̅/μ0 and = μ ̅/μ0. Other magnetic properties will be defined later in the chapter. A schematic view of the submicroscopic origins of magnetic phenomena is presented in Fig. 14.1. Most materials are diamagnetic with only a weak magnetic response induced by an applied magnetic field.

SOME HEAVY FERMION SYSTEMS AT VERY LOW TEMPERATURES

1996 ◽  
Vol 10 (04) ◽  
pp. 357-398 ◽  
Author(s):  
ERWIN A. SCHUBERTH
Keyword(s):  
Heat Capacity ◽  
Magnetic Susceptibility ◽  
Magnetic Fields ◽  
Specific Heat ◽  
Specific Heat Capacity ◽  
Superconducting State ◽  
Heavy Fermion ◽  
Fermion Systems ◽  
Heavy Fermion Systems ◽  
Squid System

The emphasis of this article lies on the properties of heavy fermion systems at the lowest temperatures obtained so far. Methods for measuring specific heat capacity and magnetic susceptibility in the milliKelvin regime are described for both low magnetic fields (<20 mT ) and high fields (<8 T ). Experimental results on UPt 3, UBe 13, and CeCu 6, are presented, and remaining problems are discussed. UPt 3 is widely regarded as the heavy Fermion system which exhibits unconventional superconductivity as demonstrated by the existence of multiple superconducting phases. Whether power laws for instance for the specific heat capacity in the superconducting state extend to T ≈ 0 instead of an exponential behavior as for BCS superconductors is a long-standing question. We have measured the specific heat capacity of several single crystals of UPt 3 in magnetic fields varying from 0 up to 7 T down to a final temperature of 10 mK . Instead of an extended power law a maximum of c(T) occurs around 20 mK, and this maximum persists in magnetic fields above B c2. It is obviously due to a new phase transition which is present both in the normal and in the superconducting state of UPt 3, slightly modified in the latter. Entropy balance above T c is fulfilled if the low-temperature peaks are included. DC-magnetization measurements on two single crystals of UPt 3 in a SQUID system yield a temperature dependence of the penetration depth ~T2 between 150 and 20 mK, considerably extending the temperature range of earlier experiments. Measurements of the anisotropic part of the magnetic susceptibility in a torque-meter indicate an additional phase line from a temperature-dependent anisotropic susceptibility to a T-independent state which is closely connected to the Bc2-line over a wide field range. No indication for a re-entrance of superconductivity is found down to 20 mK. For UBe 13 (in the superconducting state) no specific heat anomaly above 24 mK is found but a deviation from the T2.7 power law valid at higher temperatures. On a single crystal of CeCu 6 dc-magnetization measurements in various magnetic fields in a SQUID system show a plateau of the magnetic susceptibility between 400 and 50 mK, followed by an increase towards lower temperatures. An attempt to fit the low-temperature magnetization curves in several fields between 0.01 mT and 1.6 mT (minus the background from the plateau) with a Brillouin function revealed significant deviations. In 2.7 mT, the highest field applied in this experiment, however, the magnetization can be perfectly fitted assuming a tiny concentration of Gd impurities (1.5 ppm). After subtraction of the contribution due to the Gd 3+ ions from the magnetization curves in each of the lower fields a drop is revealed below 3–5 mK which gets successively quenched by the magnetic field and which has disappeared in 2.7 mT. The specific heat capacity of the same single crystal of CeCu 6 in zero magnetic field shows an increase of c/T from 1.55 J/moleK 2 at higher temperatures up to 2.8 J/moleK 2 at 11 mK. We interpret both results as due to an antiferromagnetic phase transition at 3–5 mK with the peak just not reached in the specific heat experiments.

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