Linear dependence of magnetocaloric effect on magnetic field in Mn0.6Fe0.4NiSi0.5Ge0.5 and Ni50Mn34Co2Sn14 with first-order magnetostructural transformation

Magnetocaloric effect (MCE) in the vicinity of first order martensitic transformation and second order magnetic transition in a single crystalline Ni2.13Mn0.81Ga1.06 Heusler compound was studied by a direct method. The obtained results revealed that, for the applied magnetic field strength μ0H = 1.9 T, MCE is irreversible in the vicinity of the first order martensitic transformation only when the MCE measurements are performed under cooling protocol. Plot of the experimentally measured adiabatic temperature change ΔTad as a function of temperature T indicated that ΔTad has a negligible benefit from the magnetic field-induced conversion of the high-temperature austenitic phase into the low-temperature martensitic phase and is mainly determined by the paraprocess of the austenitic phase around both direct and reverse martensitic transformations.

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Non-linear dependence of the dielectric properties of chick embryo myoblast membranes exposed to a sinusoidal 50 Hz magnetic field

International Journal of Radiation Biology ◽

10.3109/09553009109169315 ◽

1991 ◽

Vol 60 (6) ◽

pp. 877-890 ◽

Cited By ~ 7

Author(s):

Martino Grandolfo ◽

Maria Santini ◽

Paolo Vecchia ◽

Adalberto Bonincontro ◽

Cesare Cametti ◽

...

Keyword(s):

Magnetic Field ◽

Dielectric Properties ◽

Chick Embryo ◽

Linear Dependence ◽

Non Linear

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Figures of merit for stellarators near the magnetic axis

Journal of Plasma Physics ◽

10.1017/s0022377820001658 ◽

2021 ◽

Vol 87 (1) ◽

Cited By ~ 1

Author(s):

Matt Landreman

Keyword(s):

Magnetic Field ◽

Field Strength ◽

Magnetic Axis ◽

Configuration Design ◽

New Paradigm ◽

First Order ◽

Figures Of Merit ◽

Minor Radius ◽

Error Field ◽

Quantities Of Interest

A new paradigm for rapid stellarator configuration design has been recently demonstrated, in which the shapes of quasisymmetric or omnigenous flux surfaces are computed directly using an expansion in small distance from the magnetic axis. To further develop this approach, here we derive several other quantities of interest that can be rapidly computed from this near-axis expansion. First, the $\boldsymbol {\nabla }\boldsymbol {B}$ and $\boldsymbol {\nabla }\boldsymbol {\nabla }\boldsymbol {B}$ tensors are computed, which can be used for direct derivative-based optimization of electromagnetic coil shapes to achieve the desired magnetic configuration. Moreover, if the norm of these tensors is large compared with the field strength for a given magnetic field, the field must have a short length scale, suggesting it may be hard to produce with coils that are suitably far away. Second, we evaluate the minor radius at which the flux surface shapes would become singular, providing a lower bound on the achievable aspect ratio. This bound is also shown to be related to an equilibrium beta limit. Finally, for configurations that are constructed to achieve a desired magnetic field strength to first order in the expansion, we compute the error field that arises due to second-order terms.

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Magnetic field dependence of the magnetocaloric effect in magnetic nanoparticle systems: A Monte Carlo simulation

Journal of Non-Crystalline Solids ◽

10.1016/j.jnoncrysol.2006.12.042 ◽

2007 ◽

Vol 353 (8-10) ◽

pp. 793-795 ◽

Cited By ~ 9

Author(s):

D. Baldomir ◽

J. Rivas ◽

D. Serantes ◽

M. Pereiro ◽

J.E. Arias ◽

...

Keyword(s):

Magnetic Field ◽

Monte Carlo Simulation ◽

Monte Carlo ◽

Magnetocaloric Effect ◽

Field Dependence ◽

Magnetic Nanoparticle ◽

Magnetic Field Dependence

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Analytical solution for unsteady flow behind ionizing shock wave in a rotational axisymmetric non-ideal gas with azimuthal or axial magnetic field

Zeitschrift für Naturforschung A ◽

10.1515/zna-2020-0248 ◽

2021 ◽

Vol 76 (3) ◽

pp. 265-283

Author(s):

G. Nath

Keyword(s):

Magnetic Field ◽

Shock Wave ◽

Analytical Solution ◽

Axial Magnetic Field ◽

Order Approximation ◽

Ideal Gas ◽

Field Region ◽

First Order ◽

First Order Approximation ◽

Flow Variables

Abstract The approximate analytical solution for the propagation of gas ionizing cylindrical blast (shock) wave in a rotational axisymmetric non-ideal gas with azimuthal or axial magnetic field is investigated. The axial and azimuthal components of fluid velocity are taken into consideration and these flow variables, magnetic field in the ambient medium are assumed to be varying according to the power laws with distance from the axis of symmetry. The shock is supposed to be strong one for the ratio C 0 V s 2 ${\left(\frac{{C}_{0}}{{V}_{s}}\right)}^{2}$ to be a negligible small quantity, where C 0 is the sound velocity in undisturbed fluid and V S is the shock velocity. In the undisturbed medium the density is assumed to be constant to obtain the similarity solution. The flow variables in power series of C 0 V s 2 ${\left(\frac{{C}_{0}}{{V}_{s}}\right)}^{2}$ are expanded to obtain the approximate analytical solutions. The first order and second order approximations to the solutions are discussed with the help of power series expansion. For the first order approximation the analytical solutions are derived. In the flow-field region behind the blast wave the distribution of the flow variables in the case of first order approximation is shown in graphs. It is observed that in the flow field region the quantity J 0 increases with an increase in the value of gas non-idealness parameter or Alfven-Mach number or rotational parameter. Hence, the non-idealness of the gas and the presence of rotation or magnetic field have decaying effect on shock wave.

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INFLUENCE OF AN EXTERNAL MAGNETIC FIELD ON THE DYNAMICS OF A NEW-PHASE NUCLEUS IN THE VICINITY OF THE FIRST-ORDER PHASE TRANSITION IN MAGNETS WITH DEFECTS PRESENT

Modern Physics Letters B ◽

10.1142/s0217984912501837 ◽

2012 ◽

Vol 26 (28) ◽

pp. 1250183 ◽

Cited By ~ 5

Author(s):

VLADIMIR NAZAROV ◽

RISHAT SHAFEEV

Keyword(s):

Magnetic Field ◽

Phase Transition ◽

External Magnetic Field ◽

Magnetic Anisotropy ◽

Spin Reorientation ◽

Critical Fields ◽

First Order ◽

Phase Nucleus ◽

First Order Phase Transition ◽

New Phase

Theoretically, with the aid of a soliton model, the evolution of a new-phase nucleus near the first-order spin-reorientation phase transition in magnets has been investigated in an external magnetic field. The influence of an external field and one-dimensional defects of magnetic anisotropy on the dynamics of such nucleus has been demonstrated. The conditions for the localization of the new-phase nucleus in the region of the magnetic anisotropy defect and for its escape from the defect have been determined. The values of the critical fields which bring about the sample magnetization reversal have been identified and estimated.

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Doppler-Shifted Cyclotron Resonance in Thin Metal Films

Canadian Journal of Physics ◽

10.1139/p72-283 ◽

1972 ◽

Vol 50 (18) ◽

pp. 2122-2137

Author(s):

R. Turner ◽

J. F. Cochran

Keyword(s):

Magnetic Field ◽

Metal Films ◽

Thin Metal Film ◽

Thin Metal ◽

Free Electrons ◽

Fermi Surfaces ◽

First Order ◽

Simple Quantum ◽

The Magnetic Field ◽

Good Agreement

According to Van Gelder the microwave absorption by a thin metal film in the presence of a static magnetic field normal to the film contains a series of peaks as the magnetic field is varied. In the present paper it is argued that these peaks correspond to Doppler-shifted cyclotron resonances of the carriers in the metal due to the quantization of electron momenta normal to the plane of the film. A simple quantum calculation is presented for the case of free electrons where the film is thin enough that to first order the microwave fields within are determined only by the boundary conditions and Maxwell's equations. The quantum expression is in good agreement with the absorption calculated using semiclassical arguments which can be readily extended to more complicated Fermi surfaces.

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Reversibility of the Magnetocaloric Effect in the Bean-Rodbell Model

Magnetochemistry ◽

10.3390/magnetochemistry7050060 ◽

2021 ◽

Vol 7 (5) ◽

pp. 60

Author(s):

Luis M. Moreno-Ramírez ◽

Victorino Franco

Keyword(s):

Magnetic Field ◽

Thermal Hysteresis ◽

Entropy Change ◽

Second Order ◽

Zero Field ◽

First Order ◽

Magnetic Field Change ◽

Magnetocaloric Materials ◽

Moderate Magnetic Field ◽

The Magnetic Field

The applicability of magnetocaloric materials is limited by irreversibility. In this work, we evaluate the reversible magnetocaloric response associated with magnetoelastic transitions in the framework of the Bean-Rodbell model. This model allows the description of both second- and first-order magnetoelastic transitions by the modification of the η parameter (η<1 for second-order and η>1 for first-order ones). The response is quantified via the Temperature-averaged Entropy Change (TEC), which has been shown to be an easy and effective figure of merit for magnetocaloric materials. A strong magnetic field dependence of TEC is found for first-order transitions, having a significant increase when the magnetic field is large enough to overcome the thermal hysteresis of the material observed at zero field. This field value, as well as the magnetic field evolution of the transition temperature, strongly depend on the atomic magnetic moment of the material. For a moderate magnetic field change of 2 T, first-order transitions with η≈1.3−1.8 have better TEC than those corresponding to stronger first-order transitions and even second-order ones.

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High magnetic field NMR investigation of the spin density wave phase of TMTSF2PF6

Journal de Physique IV (Proceedings) ◽

10.1051/jp4:20020445 ◽

2002 ◽

Vol 12 (9) ◽

pp. 389-389

Author(s):

W. G. Clark ◽

F. Zamborsky ◽

B. Alavi ◽

P. Vonlanthen ◽

W. Moulton ◽

...

Keyword(s):

Magnetic Field ◽

Spin Density ◽

Density Wave ◽

Spin Density Wave ◽

Proton Relaxation ◽

High Magnetic Fields ◽

Organic Conductor ◽

First Order ◽

The Magnetic Field ◽

Very High

We report proton NMR measurements of the effect of very high magnetic fields up to 44.7 T (1.9 GHz) on the spin density wave (SDW) transition of the organic conductor TMTSF2PF6. Up to 1.8 GHz, no effect of critical slowing close to the transition is seen on the proton relaxation rate (1/T1), which is determined by the SDW fluctuations associated with the phase transition at the NMR frequency. Thus, the correlation time for such fluctuations is less than $1O^{-10}$s. A possible explanation for the absence of longer correlation times is that the transition is weakly first order, so that the full critical divergence is never achieved. The measurements also show a dependence of the transition temperature on the orientation of the magnetic field and a quadratic dependence on its magnitude that agrees with earlier transport measurements at lower fields. The UCLA part of this work was supported by NSF Grant DMR-0072524.

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Oxidation of Nickel(II) and Manganese(II) by Peroxodisulfate in Aqueous Solution in the Presence of Molybdate. Crystal Structure of the (NH4)6[NiMo9O32].6H2O Product

Australian Journal of Chemistry ◽

10.1071/ch9921943 ◽

1992 ◽

Vol 45 (12) ◽

pp. 1943 ◽

Cited By ~ 12

Author(s):

SJ Dunne ◽

RC Burns ◽

GA Lawrance

Keyword(s):

Rate Constant ◽

Linear Dependence ◽

Ph Dependence ◽

Order Rate Constant ◽

X Ray Diffraction ◽

X Ray ◽

First Order ◽

Oxidant Concentration ◽

Ph Range ◽

Kinetics Of

Oxidation of Ni2+,aq, by S2O82- to nickel(IV) in the presence of molybdate ion, as in the analogous manganese system, involves the formation of the soluble heteropolymolybdate anion [MMogO32]2- (M = Ni, Mn ). The nickel(IV) product crystallized as (NH4)6 [NiMogO32].6H2O from the reaction mixture in the rhombohedra1 space group R3, a 15.922(1), c 12.406(1) � ; the structure was determined by X-ray diffraction methods, and refined to a residual of 0.025 for 1741 independent 'observed' reflections. The kinetics of the oxidation were examined at 80 C over the pH range 3.0-5.2; a linear dependence on [S2O82-] and a non-linear dependence on l/[H+] were observed. The influence of variation of the Ni/Mo ratio between 1:10 and 1:25 on the observed rate constant was very small at pH 4.5, a result supporting the view that the precursor exists as the known [NiMo6O24H6]4- or a close analogue in solution. The pH dependence of the observed rate constant at a fixed oxidant concentration (0.025 mol dm-3) fits dequately to the expression kobs = kH [H+]/(Ka+[H+]) where kH = 0.0013 dm3 mol-1 s-1 and Ka = 4-0x10-5. The first-order dependence on peroxodisulfate subsequently yields a second-order rate constant of 0.042 dm3 mol-1 s-1. Under analogous conditions, oxidation of manganese(II) occurs eightfold more slowly than oxidation of nickel(II), whereas oxidation of manganese(II) by peroxomonosulfuric acid is 16-fold faster than oxidation by peroxodisulfate under similar conditions.

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