scholarly journals The effective susceptibility of a paramagnetic powder

1941 ◽  
Vol 178 (972) ◽  
pp. 86-92 ◽  
Keyword(s):  
Magnetic Field ◽  
Magnetic Material ◽  
External Magnetic Field ◽  
Curie Temperature ◽  
Temperature Scale ◽  
Preceding Paper ◽  
Theoretical Expression ◽  
Demagnetizing Field ◽  
Definition Of ◽  
Packed Powder

The effective susceptibility (that is, the magnetic moment divided by the external magnetic field) of a paramagnetic powder loosely packed into an ellipsoidal container has been measured against the vapour pressure of liquid helium, and hence, using the results of the preceding paper, against the susceptibility of the compact salt. The definition of the ‘Curie’ temperature scale is based on the latter, and it is found that the correction to be applied in calculating the Curie temperature from the effective susceptibility of the powder agrees with that given by a theoretical expression derived from Breit’s calculation of the demagnetizing field of a powder. This is of importance both in experiments using a loosely packed powder and in experiments using a paramagnetic powder mixed with a non-magnetic material.

scholarly journals On the crustal bias of repeat stations in Romania

2013 ◽  
Vol 55 (6) ◽  
Author(s):  
Venera Dobrica ◽  
Crisan Demetrescu ◽  
Razvan Greculeasa ◽  
Anca Isac
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Curie Temperature ◽  
Magnetic Induction ◽  
Electromagnetic Induction ◽  
Reference Station ◽  
Lateral Variation ◽  
Field Campaigns ◽  
Induction Model ◽  
Geomagnetic Measurements

<p>A magnetic induction model has been applied to recordings obtained in 2010 during the field campaigns for geomagnetic measurements at the 26 repeat stations of the Romanian secular variation network. The model is based on the observation that a variable external magnetic field induces a response of the Earth's interior not only by electromagnetic induction, but also by magnetic induction in the magnetic rocks above the Curie temperature. The model computes coefficients of a linear relationship between recorded values of a certain geomagnetic element (X, Y, Z, or F) at the repeat station and recorded X, Y, Z values at a reference station (in this case, SUA observatory). Coefficients depend on magnetic permeabilities of rocks beneath the station and stand as a proxy for the anomaly bias characterizing the site. Maps of the lateral variation of this type of information were obtained and discussed.</p>

Magnetization and Curie Temperature of Ferromagnetic Ultrathin Films: The Influence of Magnetic Anisotropy and Dipolar Interactions (invited)

1991 ◽  
Vol 231 ◽  
Author(s):  
P. Bruno
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Curie Temperature ◽  
Magnetic Anisotropy ◽  
Long Range ◽  
Ultrathin Films ◽  
Experimental Results ◽  
Dipolar Interactions ◽  
Surface Gradient ◽  
Theoretical Investigations

AbstractTheoretical investigations of the magnetization and Curie temperature of ferromagnetic ultrathin films in the presence of magnetic anisotropy and long-range dipolar interactions are presented. The Curie temperature of fcc (001) cobalt ultrathin films is calculated and compared with experimental results on Co/Cu (001) films. The influence of an external magnetic field, and the surface gradient of the magnetization are also discussed.

scholarly journals A Method of the Riemann–Hilbert Problem for Zhang’s Conjecture 2 in a Ferromagnetic 3D Ising Model: Topological Phases

Mathematics ◽  
2021 ◽  
Vol 9 (22) ◽  
pp. 2936
Author(s):  
Zhidong Zhang ◽  
Osamu Suzuki
Keyword(s):  
Magnetic Field ◽  
Ising Model ◽  
External Magnetic Field ◽  
Hilbert Problem ◽  
Three Dimensional ◽  
Preceding Paper ◽  
Mathematical Structure ◽  
Topological Phases ◽  
Riemann Hilbert Problem ◽  
3D Ising Model

A method of the Riemann–Hilbert problem is employed for Zhang’s conjecture 2 proposed in Philo. Mag. 87 (2007) 5309 for a ferromagnetic three-dimensional (3D) Ising model in a zero external magnetic field. In this work, we first prove that the 3D Ising model in the zero external magnetic field can be mapped to either a (3 + 1)-dimensional ((3 + 1)D) Ising spin lattice or a trivialized topological structure in the (3 + 1)D or four-dimensional (4D) space (Theorem 1). Following the procedures of realizing the representation of knots on the Riemann surface and formulating the Riemann–Hilbert problem in our preceding paper [O. Suzuki and Z.D. Zhang, Mathematics 9 (2021) 776], we introduce vertex operators of knot types and a flat vector bundle for the ferromagnetic 3D Ising model (Theorems 2 and 3). By applying the monoidal transforms to trivialize the knots/links in a 4D Riemann manifold and obtain new trivial knots, we proceed to renormalize the ferromagnetic 3D Ising model in the zero external magnetic field by use of the derivation of Gauss–Bonnet–Chern formula (Theorem 4). The ferromagnetic 3D Ising model with nontrivial topological structures can be realized as a trivial model on a nontrivial topological manifold. The topological phases generalized on wavevectors are determined by the Gauss–Bonnet–Chern formula, in consideration of the mathematical structure of the 3D Ising model. Hence we prove the Zhang’s conjecture 2 (main theorem). Finally, we utilize the ferromagnetic 3D Ising model as a platform for describing a sensible interplay between the physical properties of many-body interacting systems, algebra, topology, and geometry.

Neutron–antineutron oscillation and discrete symmetries

2018 ◽  
Vol 33 (31) ◽  
pp. 1844016 ◽  
Author(s):  
Zurab Berezhiani ◽  
Arkady Vainshtein
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Text Classification ◽  
Discrete Symmetries ◽  
Rotational Invariance ◽  
Baryon Charge ◽  
Free Particles ◽  
Definition Of ◽  
Charge Formula

We analyze status of [Formula: see text], [Formula: see text] and [Formula: see text] discrete symmetries in application to neutron–antineutron transitions breaking conservation of baryon charge [Formula: see text] by two units. At the level of free particles, all these symmetries are preserved. This includes [Formula: see text] reflection in spite of the opposite internal parities usually ascribed to neutron and antineutron. Explanation, which goes back to the 1937 papers by Majorana and Racah, is based on a definition of parity satisfying [Formula: see text], instead of [Formula: see text], and ascribing [Formula: see text] to both, neutron and antineutron. We apply this to [Formula: see text], [Formula: see text] and [Formula: see text] classification of six-quark operators with [Formula: see text]. It allows to specify operators contributing to neutron–antineutron oscillations. Remaining operators contribute to other [Formula: see text] processes and, in particular, to nuclei instability. We also show that presence of external magnetic field does not induce any new operator mixing the neutron and antineutron provided that rotational invariance is not broken.

Synthesis and Characterization of Cobalt(II) Salicylaldimine Complex Supported on Silica Covered Magnetite

2014 ◽  
Vol 69 (5) ◽  
Author(s):  
Mohamad Haqzim Ayob ◽  
Jon Efendi ◽  
Lai Sin Yuan ◽  
Sheela Chandren ◽  
Ho Chin Siong ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Material ◽  
Schiff Base ◽  
External Magnetic Field ◽  
High Surface ◽  
Schiff Base Complex ◽  
Reduction Process ◽  
Precipitation Method ◽  
Support Material ◽  
Base Complex

Cobalt Schiff base complex is widely used in many reactions such as reduction process, carbonylation of alcohol and oxidation of alkenes. Generally, this catalyst is in the powder form. It is difficult to separate the catalyst from the reaction mixture due to the small particles size of the catalyst. One way to easily separate the catalyst is by applying external magnetic field. However these catalysts would have to possess magnetic properties for this method to work on. One of the strategies to solve this problem is by adding magnetic material into the catalysts. Magnetite is a common magnetic material used as a support material which can be synthesized by the co-precipitation method of Fe2+ andFe3+. Normally, magnetite is covered by silica in order to stabilize and reduce its toxicity. This can be done by using the sol-gel approach. Silica coated magnetite is widely used as a support material because of its high surface area and easy catalyst separation after the reaction simply by applying an external magnetic field. In this research, cobalt Schiff base complex/silica@magnetite was synthesized from the condensation of cobalt (II) salicylaldehyde with 3-aminopropyltrimethoxy silane on the surface of silica@magnetite. The catalysts were characterized using Fourier transform infrared spectrometer, scanning electron microscopy and diffuse reflectance ultra-violet visible spectrometry. 

scholarly journals External Magnetic Field Measurements in UME Kibble Balance

ACTA IMEKO ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 33
Author(s):  
Haci Ahmedov ◽  
Beste Korutlu ◽  
Lev Dorosinskiy ◽  
Recep Orhan ◽  
Ozlen Tuncel
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Vertical Direction ◽  
Field Measurements ◽  
Magnetic Flux Density ◽  
National Metrology Institute ◽  
Mass Unit ◽  
Long Term Stability ◽  
Faraday’S Law ◽  
Definition Of

The new definition of kilogram in terms of the fixed value of Planck constant ensures the long-term stability of SI mass unit and enables traceability from more than one source. Kibble balance experiments offer an effective primary realization method for the new definition of kilogram. Kibble Balance apparatus operating at National Metrology Institute of Turkey is designed with a stationary coil and an oscillating magnet. In contradistinction to traditional moving coil Kibble balance experiments, external magnetic field brings an asymmetry between the Ampere’s law of force and the Faraday’s law of induction in moving magnet experiments. In this paper, we develop a method based on the external magnetic flux density difference measurements in vertical direction to take into account the effect of the external magnetic field on the realization of kilogram. The proposed model in this approach fits well with the data such that the kilogram realization requirement is met within the accuracy of the measuring instrument.

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