Coronal Magnetic Structure: the Role of Ideal MHD Invariants

1991 ◽  
pp. 570-581 ◽  
Author(s):  
Mitchell A. Berger
Keyword(s):  
Magnetic Structure ◽  
Ideal Mhd

scholarly journals Concurrent effect of Alfvén waves and planar magnetic structure on geomagnetic storms

2019 ◽  
Vol 490 (3) ◽  
pp. 3440-3447 ◽  
Author(s):  
Zubair I Shaikh ◽  
Anil Raghav ◽  
Geeta Vichare ◽  
Ankush Bhaskar ◽  
Wageesh Mishra ◽  
...  
Keyword(s):  
Magnetic Structure ◽  
Geomagnetic Storms ◽  
Recovery Phase ◽  
Alfven Waves ◽  
Magnetic Clouds ◽  
Alfvén Waves ◽  
Fast Recovery ◽  
Interplanetary Coronal Mass Ejection ◽  
Mass Ejection

ABSTRACT Generally, interplanetary coronal mass ejection (ICME) triggers intense and strong geomagnetic storms. It has been established that the ICME sheath-moulded planar magnetic structure enhances the amplitude of the storms. Alfvén waves embedded in ICME magnetic clouds or high solar streams including corotating interacting regions (CIRs) in turn extend the recovery phase of the storm. Here, we investigate a geomagnetic storm with a very complex temporal profile with multiple decreasing and recovery phases. We examine the role of planar magnetic structure (PMS) and Alfvén waves in the various phases of the storm. We find that fast decrease and fast recovery phases are evident during transit of PMS regions, whereas a slight decrease or recovery is found during the transit of regions embedded with Alfvénic fluctuations.

Role of electron-lattice interactions in determining the magnetic structure of insulating manganites

1999 ◽  
Vol 09 (PR10) ◽  
pp. Pr10-335-Pr10-336 ◽  
Author(s):  
M. Capone ◽  
D. Feinberg ◽  
M. Grilli
Keyword(s):  
Magnetic Structure

Role of Magnetic Subsystems to Form a Complex Magnetic Structure Mn2GeO4 Single Crystals

2015 ◽  
Vol 233-234 ◽  
pp. 129-132 ◽  
Author(s):  
Nikita V. Volkov ◽  
N.V. Mikhashenok ◽  
K.A. Sablina ◽  
A.I. Pankrats ◽  
V.I. Tugarinov ◽  
...  
Keyword(s):  
Single Crystals ◽  
Magnetic Structure ◽  
Low Temperatures ◽  
Spin Reorientation ◽  
Manganese Ions ◽  
Resonance Properties ◽  
Spiral Magnetic Structure

Present paper reports of resonance properties of Mn2GeO4 single crystals. The data confirm the formation of a complex spiral magnetic structure at low temperatures. It is shown that the spin reorientation may be associated with the competition anisotropic contributions of the various subsystems of the manganese ions.

Defect induced ferromagnetic interaction in nanostructured nickel oxide with core–shell magnetic structure: the role of Ni2+ and O2− vacancies

2016 ◽  
Vol 18 (17) ◽  
pp. 12135-12148 ◽  
Author(s):  
G. Madhu ◽  
K. Maniammal ◽  
V. Biju
Keyword(s):  
Nickel Oxide ◽  
Magnetic Structure ◽  
Core Shell ◽  
Ferromagnetic Interaction

O2− vacancies act as donor impurities and mediate ferromagnetic interaction between spins associated with uncompensated and partially compensated Ni2+ vacancies.

High Coercivity Mechanism Of The Die-Upset Hard Magnets Re13.75Fe80.25B6 (Re = Nd, Pr): Possible Correlation To Specific DefectMicrostructure

1999 ◽  
Vol 5 (S2) ◽  
pp. 42-43
Author(s):  
V.V. Volkov ◽  
Y. Zhu
Keyword(s):  
Magnetic Structure ◽  
Permanent Magnets ◽  
Materials Science ◽  
High Energy ◽  
High Coercivity ◽  
Energy Product ◽  
Hard Magnets ◽  
Energy Products ◽  
Processing Techniques

The magnetic properties of permanent magnets are sensitive to their microstructure. In particular, for the family of Nd(Pr)-Fe-B magnets a very different coercivity and energy products may be obtained by several processing techniques. It was experimentally found that a small excess of Nd over the exact phase composition of Nd2Fe14B plays an important role in obtaining high-energy products during the die-upset processing of the anisotropic hard magnets. However the specific role of the Nd excess on both magnetic structure and microstructure of these die-upset magnets is unclear and controversial. Answers to these questions may help to correctly address some major issues in materials science, e.g. how microstructure is related to magnetic structure of hard magnets, and how to optimize the performance of hard magnets.In-situ TEM magnetizing experiments combined with Lorentz magnetic microscopy in Fresnel-Foucault modes were used to characterize the magnetic structure of die-upset, high energy-product hard magnets Nd13.75Fe80.25B6 and Pr13.75Fe80.25B6.

scholarly journals Evolution of magnetism on a curved nano-surface

Nanoscale ◽  
2015 ◽  
Vol 7 (30) ◽  
pp. 12878-12887 ◽  
Author(s):  
D. G. Merkel ◽  
D. Bessas ◽  
Z. Zolnai ◽  
R. Rüffer ◽  
A. I. Chumakov ◽  
...  
Keyword(s):  
Magnetic Structure ◽  
Layer Thickness ◽  
Interparticle Distance ◽  
Magnetic Layer ◽  
Magnetic Nanostructures ◽  
Magnetic Behaviour ◽  
Nanoparticle Size ◽  
Magnetic Domains

The role of nanoparticle size, interparticle distance and magnetic layer thickness on the formation of magnetic nanostructures was studied. Individual magnetic behaviour was found for the 400 nm spheres and a collective magnetic structure for the 25 nm balls where magnetic domains spread over several particles.

scholarly journals Atomic, electronic and magnetic structure of graphene/iron and nickel interfaces: theory and experiment

RSC Advances ◽  
2015 ◽  
Vol 5 (12) ◽  
pp. 9173-9179 ◽  
Author(s):  
D. W. Boukhvalov ◽  
Y. N. Gornostyrev ◽  
M. A. Uimin ◽  
A. V. Korolev ◽  
A. Y. Yermakov
Keyword(s):  
Magnetic Properties ◽  
Magnetic Structure ◽  
Significant Influence ◽  
Electronic And Magnetic Structure ◽  
Theory And Experiment

Experiments and theory demonstrate the significant influence of a graphene cover to the magnetic properties of an iron substrate and the insignificant role of nickel.

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