Moment Comparison of Two Decoupling Procedures for Green Function Equations

1971 ◽  
Vol 49 (6) ◽  
pp. 776-779
Author(s):  
Barry Frank
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Green Function ◽  
Resonance Line ◽  
Approximation Scheme ◽  
Model System ◽  
Point Of View ◽  
Paramagnetic Resonance ◽  
Ising System ◽  
Line Shapes

A recently developed moment theorem and an approximation scheme of Pryce and Stevens are used to compare 2nd-RPA and Tomita–Tanaka type decoupling procedures for Green function equations. The comparison is accomplished from the point of view of the moments of the paramagnetic resonance line shapes that the decouplings generate. An Ising system in an external magnetic field is taken as the model system. It is found that use of the more complicated 2nd RPA is justified only if accuracy to O(1/z2) is desired.

THE COMPENSATION BEHAVIOR AND INITIAL SUSCEPTIBILITIES OF A MIXED-SPIN HEISENBERG FERRIMAGNETIC SYSTEM IN AN EXTERNAL MAGNETIC FIELD

2007 ◽  
Vol 21 (07) ◽  
pp. 1077-1087 ◽  
Author(s):  
JUN LI ◽  
AN DU ◽  
GUOZHU WEI
Keyword(s):  
Magnetic Field ◽  
Magnetic Properties ◽  
Transition Temperature ◽  
External Magnetic Field ◽  
Green Function ◽  
Compensation Point ◽  
Function Technique ◽  
Honeycomb Lattice ◽  
Mixed Spin ◽  
Compensation Behavior

The magnetic properties of a mixed spin-2 and spin-5 / 2 Heisenberg ferrimagnetic system on a layered honeycomb lattice are investigated theoretically by a multisublattice Green-function technique which takes into account the quantum nature of Heisenberg spins. We calculate the magnetization and the compensation temperature and transition temperature of the system in an external magnetic field and in a zero external magnetic field, and find that the transition temperature of the system increases on the effect of an external magnetic field, the compensation point disappears when the single-ion anisotropy is not large and there are two compensation points when the anisotropy is large. We also calculate the initial susceptibilities of the system.

scholarly journals Method of Measuring Deformations of Magnetoactive Elastomers under the Action of Magnetic Fields

2019 ◽  
Vol 7 (4) ◽  
pp. 81-91 ◽  
Author(s):  
D. V. Saveliev ◽  
L. Yu. Fetisov ◽  
D. V. Chashin ◽  
P. A. Shabin ◽  
D. A. Vyunik ◽  
...  
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Polymer Matrix ◽  
Deep Understanding ◽  
Soft Materials ◽  
Point Of View ◽  
Magnetic Microparticles ◽  
Deformation Curves ◽  
Uniform External Magnetic Field ◽  
Manufacturing Technologies

Magnetic deformation is a change in the size and shape of a sample under the action of a uniform external magnetic field. The study of this effect in various materials provides deep understanding of the nature of magnetic and mechanical interactions. Moreover, magnetic deformation is of great interest from an engineering point of view for designing new devices. In magnetoactive elastomers containing magnetic microparticles in the polymer matrix, a giant deformation is detected under the action of an external magnetic field. The generally accepted methods for measuring magnetic deformation in magnetoactive soft materials are now practically absent. The article describes the installation for the study of the magnetomechanical characteristics of magnetoactive elastomers and demonstrates its experimental capabilities. The installation allows to measure deformations in the range from 0 to 12.5 mm with a resolution of 1 micron. The deformation curves obtained using these installations are required for developing actuators and sensors based on magnetoactive elastomers, and also for improving their manufacturing technologies.

scholarly journals On the Formation of Nanocrystalline Grains in Metallic Glasses by Means of In-Situ Nuclear Forward Scattering of Synchrotron Radiation

Nanomaterials ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 544 ◽  
Author(s):  
David Smrčka ◽  
Vít Procházka ◽  
Vlastimil Vrba ◽  
Marcel Miglierini
Keyword(s):  
Magnetic Field ◽  
Synchrotron Radiation ◽  
External Magnetic Field ◽  
Metallic Glasses ◽  
Hyperfine Interactions ◽  
Transformation Process ◽  
Forward Scattering ◽  
Point Of View ◽  
Nuclear Forward Scattering

Application of the so-called nuclear forward scattering (NFS) of synchrotron radiation is presented for the study of crystallization of metallic glasses. In this process, nanocrystalline alloys are formed. Using NFS, the transformation process can be directly observed during in-situ temperature experiments not only from the structural point of view, i.e., formation of nanocrystalline grains, but one can also observe evolution of the corresponding hyperfine interactions. In doing so, we have revealed the influence of external magnetic field on the crystallization process. The applied magnetic field is not only responsible for an increase of hyperfine magnetic fields within the newly formed nanograins but also the corresponding components in the NFS time spectra are better identified via occurrence of quantum beats with higher frequencies. In order to distinguish between these two effects, simulated and experimental NFS time spectra obtained during in-situ temperature measurements with and without external magnetic field are compared.

Paramagnetic Resonance Line Shapes ofFe++in MgO

1964 ◽  
Vol 134 (1A) ◽  
pp. A128-A139 ◽  
Author(s):  
D. H. McMahon
Keyword(s):  
Resonance Line ◽  
Paramagnetic Resonance ◽  
Line Shapes

Complex atomic spectral line shapes in the presence of an external magnetic field

2002 ◽  
Vol 66 (6) ◽  
Author(s):  
M. L. Adams ◽  
R. W. Lee ◽  
H. A. Scott ◽  
H. K. Chung ◽  
L. Klein
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Spectral Line ◽  
Line Shapes
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