The Role of Dipolar Interactions in AFC-Media

2004 ◽  
Vol 40 (4) ◽  
pp. 2437-2439
Author(s):  
A. Berger ◽  
A. Moser ◽  
D.T. Margulies
Keyword(s):  
2012 ◽  
Vol 3 ◽  
pp. 4500204-4500204 ◽  
Author(s):  
N. Eibagi ◽  
J. J. Kan ◽  
F. E. Spada ◽  
E. E. Fullerton

Nanoscale ◽  
2015 ◽  
Vol 7 (17) ◽  
pp. 7717-7725 ◽  
Author(s):  
M. Campanini ◽  
R. Ciprian ◽  
E. Bedogni ◽  
A. Mega ◽  
V. Chiesi ◽  
...  

Left: morphological and magnetic characterization of magnetite NPs. Right: Lorentz microscopy unveils the role of dipolar interactions in magnetic hyperthermia of superparamagnetic NPs.


2021 ◽  
Vol 2 (1) ◽  
pp. 343-353
Author(s):  
Evgeny Nimerovsky ◽  
Kai Xue ◽  
Kumar Tekwani Movellan ◽  
Loren B. Andreas

Abstract. The radio-frequency-driven recoupling (RFDR) pulse sequence is used in magic-angle spinning (MAS) NMR to recouple homonuclear dipolar interactions. Here we show simultaneous recoupling of both the heteronuclear and homonuclear dipolar interactions by applying RFDR pulses on two channels. We demonstrate the method, called HETeronuclear RFDR (HET-RFDR), on microcrystalline SH3 samples at 10 and 55.555 kHz MAS. Numerical simulations of both HET-RFDR and standard RFDR sequences allow for better understanding of the influence of offsets and paths of magnetization transfers for both HET-RFDR and RFDR experiments, as well as the crucial role of XY phase cycling.


2008 ◽  
Vol 8 (6) ◽  
pp. 2929-2943 ◽  
Author(s):  
D. Kechrakos ◽  
K. N. Trohidou

Assemblies of magnetic nanoparticles exhibit interesting physical properties arising from the competition of intraparticle dynamics and interparticle interactions. In ordered arrays of magnetic nanoparticles magnetostatic interparticle interactions introduce collective dynamics acting competitively to random anisotropy. Basic understanding, characterization and control of dipolar interaction effects in arrays of magnetic nanoparticles is an issue of central importance. To this end, numerical simulation techniques offer an indispensable tool. We report on Monte Carlo studies of the magnetic hysteresis and spin-dependent transport in thin films formed by ordered arrays of magnetic nanoparticles. Emphasis is given to the modifications of the single-particle behavior due to interparticle dipolar interactions as these arise in quantities of experimental interest, such as, the magnetization, the susceptibility and the magnetoresistance. We investigate the role of the structural parameters of an array (interparticle separation, number of stacked monolayers) and the role of the internal structure of the nanoparticles (single phase, core–shell). Dipolar interactions are responsible for anisotropic magnetic behavior between the in-plane and out-of-plane directions of the sample, which is reflected on the investigated magnetic properties (magnetization, transverse susceptibility and magnetoresistance) and the parameters of the array (remanent magnetization, coercive field, and blocking temperature). Our numerical results are compared to existing measurements on self-assembled arrays of Fe-based and Co nanoparticles is made.


2008 ◽  
Vol 64 (4) ◽  
pp. 497-503 ◽  
Author(s):  
Urszula Rychlewska ◽  
Natalia Waścinska ◽  
Beata Warżajtis ◽  
Jacek Gawroński

This paper reports the synthesis, X-ray and NMR investigations of chiral and meso dinitriles of tartaric acid (tartarodinitriles) and their O,O′-diacetyl and O,O′-dibenzoyl derivatives. While in chiral tartaric acid its esters and NH amides the four-atom carbon chain is overwhelmingly trans, it is gauche in chiral tartarodinitriles. Conversely, meso-tartaric acid, its esters and amides display a tendency for the gauche conformation, but meso-tartarodinitriles usually have the trans conformation. The NMR studies of tartarodinitriles reveal the presence of a conformational equilibrium in solution with a preference for those conformers found in crystals. The gauche conformation of meso-tartarodinitriles seems to be stabilized by local dipolar interactions, intramolecular C—H...O hydrogen bonds and by a tendency for maximization of the gauche effect, the latter effect also operating in chiral tartarodinitriles. Stabilization of the trans conformers of tartarodinitriles in the crystals seems to originate from specific intermolecular interactions.


Sign in / Sign up

Export Citation Format

Share Document