Search results for "Magnetization"
showing 10 items of 550 documents
EFFICIENCY OF INTERNAL SHOCKS IN MAGNETIZED RELATIVISTIC JETS
2011
We study the dynamic and radiative efficiency of conversion of kinetic-to-thermal/magnetic energy by internal shocks in relativistic magnetized outflows. A parameter study of a large number of collisions of cylindrical shells is performed. We explore how, while keeping the total flow luminosity constant, the variable fluid magnetization influences the efficiency and find that the interaction of shells in a mildly magnetized jet yields higher dynamic, but lower radiative efficiency than in a non-magnetized flow. A multi-wavelength radiative signature of different shell magnetization is computed assuming that relativistic particles are accelerated at internal shocks.
Functions Characterizing the Ground State of the XXZ Spin-1/2 Chain in the Thermodynamic Limit
2013
We establish several properties of the solutions to the linear integral equations describing the infinite volume properties of the XXZ spin-1/2 chain in the disordered regime. In particular, we obtain lower and upper bounds for the dressed energy, dressed charge and density of Bethe roots. Furthermore, we establish that given a fixed external magnetic field (or a fixed magnetization) there exists a unique value of the boundary of the Fermi zone.
Magnetization relaxation in YBCO films with improved supercurrent transport properties
2010
The relaxation of the irreversible magnetization in optimally doped YBCO films with natural and artificial pinning centres was measured in zero-field cooling conditions using SQUID magnetometry. The external magnetic field H was oriented along the c axis. An appropriate method for the determination of the characteristic vortex pinning energy from the normalized vortex-creep activation energy is discussed. This is based on the existence of a crossover elastic (collective) vortex creep at low temperatures T – plastic vortex creep at high T, caused by the T dependent macroscopic currents induced in the sample during magnetization measurements.
Synthesis and characterization of a new layered organic-inorganic hybrid nickel(II) 1,4 : 5,8-naphthalenediimide bis-phosphonate, exhibiting canted a…
2008
A new Ni(II) layered hybrid organic-inorganic compound of formula Ni{sub 2}[(NDI-BP)(H{sub 2}O){sub 2}].2H{sub 2}O has been prepared in very mild conditions from N,N'-bis(2-phosphonoethyl)napthalene-1,4:5,8-tetracarboximide (NDI-BP ligand) and NiCl{sub 2}. The X-ray powder structure characterization of the title compound suggests a pillared layered organic-inorganic hybrid structure. The distance between the organic and inorganic layers has been found to be 17.8 A. The inorganic layers consist of corner sharing [NiO{sub 5}(H{sub 2}O)] octahedra and they are pillared by the diphosphonate groups. DC and AC magnetic measurements as a function of temperature and field indicate the presence of 2…
Towards Large-Scale Steady-State Enhanced Nuclear Magnetization with In Situ Detection
2021
Signal Amplification By Reversible Exchange (SABRE) boosts NMR signals of various nuclei enabling new applications spanning from magnetic resonance imaging to analytical chemistry and fundamental physics. SABRE is especially well positioned for continuous generation of enhanced magnetization on a large scale, however, several challenges need to be addressed for accomplishing this goal. Specifically, SABRE requires (i) a specialized catalyst capable of reversible H2 activation and (ii) physical transfer of the sample from the point of magnetization generation to the point of detection (e.g., a high-field or a benchtop NMR spectrometer). Moreover, (iii) continuous parahydrogen bubbling accele…
Slow relaxation of the magnetization in a 4,2-wavelike Fe(III)2Co(II) heterobimetallic chain.
2012
The reaction of the low-spin iron(III) complex [Fe(dmbpy)(CN)(4)](-) (1) with fully solvated cobalt(II) ions affords the cyanide-bridged heterobimetallic chain {[Fe(III)(dmbpy)(CN)(4)](2)Co(II)(H(2)O)(2)}(n) · 4nH(2)O (2), which exhibits intrachain ferromagnetic coupling and double slow relaxation of the magnetization.
[Fe(III)(dmbpy)(CN)4]-: a new building block for designing single-chain magnets.
2012
We herein present the synthesis and magneto-structural study of a new family of heterobimetallic chains of general formula {[Fe(III)(dmbpy)(CN)(4)](2)M(II)(H(2)O)(2)}(n)·pnH(2)O [dmbpy = 4,4'-dimethyl-2,2'-bipyridine; M = Mn (2), Cu (3), Ni (4) and Co (5) with p = 4 (2), 3 (3), 9 (4) and 3.5 (5)] which were prepared by using the mononuclear PPh(4)[Fe(III)(dmbpy)(CN)(4)]·3H(2)O (1) building block (PPh(4)(+) = tetraphenylphosphonium) as a ligand toward fully solvated M(II) ions. The structure of 1 consists of discrete [Fe(III)(dmbpy)(CN)(4)](-) anions, tetraphenylphosphonium cations and noncoordinated water molecules. Complexes 2-5 are isostructural compounds whose structure consists of neutr…
Field-induced slow magnetic relaxation in mixed valence di- and tri-nuclear CoII–CoIII complexes
2020
Two novel mixed valence CoII–CoIII complexes, namely [CoIICoIII(L1)(ab)(mb)2(H2O)]·dmf (1) and [CoIII2CoII(L2)4(H2O)4]·2H2O (2) [H2L1 = (E)-2-((1-hydroxybutan-2-ylimino)methyl)-6-methoxyphenol, ab = 2-amino-butan-1-ol anion, mb = p-methyl benzoate, H2L2 = 3-((2-hydroxy-3-methoxy-benzylidene)-amino)-propionic acid, and dmf = N,N-dimethyl-formamide], were synthesized and characterized by single crystal X-ray diffraction and magnetic studies at low temperature. The structure determination reveals that both complexes belong to the monoclinic system with P21/c (1) and I2/a (2) space groups. Complex 1 is a dinuclear CoIIICoII compound with distorted octahedral cobalt centers showing different coo…
Slow relaxation of magnetization in a {Fe6Dy} complex deriving from a family of highly symmetric metallacryptands
2019
The synthesis and characterization of a new family of isostructural {Fe6Ln} complexes, (pipH)3{Fe6Ln(shiH)3(shi)6}·1.5 pip·xH2O (Ln = Gd (1), Dy (2), Tb (3) and Y (4), pip = piperidine, and shi3− = salicylhydroxamic acid) is reported. The resulting compounds possess an exceptionally unique structure of a metallacrown-like motif while the overall complexes feature more the structure of metallacryptates. Magnetic studies are reported and reveal that the {Fe6Dy} analogue belongs to the single-molecule magnet (SMM) family.
Exploring the Role of Intramolecular Interactions in the Suppression of Quantum Tunneling of the Magnetization in a 3d-4f Single-Molecule Magnet.
2021
Hydroxide-bridged FeIII4LnIII2 clusters having the general formula [Fe4Ln2(μ3-OH)2(mdea)6(SCN)2(NO3)2(H2O)2]·4H2O·2MeCN {Ln = Y (1), Dy (2), mdea = N-methyldiethanolamine} were synthesized and magnetically characterized. The thermal relaxation of the magnetization for 2 and the diluted FeIII4DyIIIYIII complex 3 (with and without applied field) has been analyzed. The diluted sample shows a dominant QTM at low temperatures that can be removed with a 0.15 T dc field. Both 2 and 3 show moderately high Ueff barriers and exhibit hysteresis loops until 5 K.