Effect Of Strong Magnetic Field Research Articles

Quark matter with strong magnetic field and possibility of the third family of compact stars

We consider the possibility for the existence of the third family of compact objects, considering the effect of strong magnetic fields inside the hybrid stars. As a result, we demonstrate such new sequences of stable equilibrium configurations for some hadronic equations of state. Through the analysis of the adiabatic index inside stars, we find the conditions for appearing the third family of compact objects, i.e., for hadronic stars without quarks, that the maximum mass should be small, the central density for the maximum mass should be also small, and the radius for the the maximum mass should be large. Even for soft hadronic equations of state, the two solar-mass stars might survive as the third family of compact objects, once quark matter with strong magnetic field, such as $\sim {\cal O}(10^{19} {\rm G})$, is taken into account. It might give a hint to solve the so-called hyperon puzzle in nuclear physics.

Multiferroic Bi0.65La0.35Fe0.5Sc0.5O3 perovskite: Magnetic and thermodynamic properties

Magnetic and thermodynamic properties of polycrystalline multiferroic Bi0.65La0.35Fe0.5Sc0.5O3 synthesized under high-pressure and high-temperature conditions are reported. Magnetic properties were studied using a SQUID magnetometer technique over the temperature range of 5−300K in magnetic fields up to H=10kOe. The field dependent magnetization M(H) was measured in magnetic fields up to 50kOe at different temperatures up to 230K after zero-field cooling procedure. A long-range magnetic ordering of the AFM type with a weak FM contribution occurs below the Néel temperature TN ~237K. Magnetic hysteresis loops taken below TN show a huge coercive field up to Hc ~10kOe. A strong effect of magnetic field on the magnetic properties of the compound has been found. Derivative of the initial magnetization curves demonstrates a temperature-dependent anomaly in fields of H=15−25kOe. Besides, an anomaly of the temperature dependent zero-field cooled magnetization measured in magnetic fields of 6−7kOe has been found. Origin of both anomalies is associated with inhomogeneous magnetic state of the compound. The heat capacity has been measured from 2K up to room temperature and a significant contribution from the magnon excitations at low temperatures has been detected. From the low-temperature heat capacity, an anisotropy gap of the magnon modes of the order 3.7meV and Debye temperature TD=189K have been determined.

Effect of Strong Magnetic Field on Competing Order Parameters in Two-Flavor Dense Quark Matter

We study the effect of strong magnetic field on competing chiral and diquark order parameters in a regime of moderately dense quark matter. The interdependence of the chiral and diquark condensates through nonperturbative quark mass and strong coupling effects is analyzed in a two-flavor Nambu-Jona-Lasinio (NJL) model. In the weak magnetic field limit, our results agree qualitatively with earlier zero-field studies in the literature that find a critical coupling ratioGD/GS~1.1below which chiral or superconducting order parameters appear almost exclusively. Above the critical ratio, there exists a significant mixed broken phase region where both gaps are nonzero. However, a strong magnetic fieldB≳1018 G disrupts this mixed broken phase region and changes a smooth crossover found in the weak-field case to a first-order transition for both gaps at almost the same critical density. Our results suggest that in the two-flavor approximation to moderately dense quark matter strong magnetic field enhances the possibility of a mixed phase at high density, with implications for the structure, energetics, and vibrational spectrum of neutron stars.

Thomas-Fermi and Thomas-Fermi-Dirac models in two-dimension – Effect of strong quantizing magnetic field

Using Thomas-Fermi (TF) and Thomas-Fermi-Dirac (TFD) models, we have investigated the properties of electron gas inside two-dimensional (2D) Wigner-Seitz (WS) cells in presence of a strong orthogonal quantizing magnetic field. The electron-electron Coulomb exchange interaction in quasi-2D case is obtained. The exact form of exchange term in 2D is derived making the width of the system tending to zero. Further, using the exchange term, the Thomas-Fermi-Dirac equation in 2D is established. It has been observed that only the ionized WS cell can have finite radius in the Thomas-Fermi model, even in presence of a strong quantizing magnetic field. On the other hand, in the Thomas-Fermi-Dirac model a neutral WS cell can have finite radius.

Engineering an Artificial Flavoprotein Magnetosensor.

Migratory birds use the Earth's magnetic field as a source of navigational information. This light-dependent magnetic compass is thought to be mediated by cryptochrome proteins in the retina. Upon light activation, electron transfer between the flavin adenine dinucleotide cofactor and tryptophan residues leads to the formation of a spin-correlated radical pair, whose subsequent fate is sensitive to external magnetic fields. To learn more about the functional requirements of this complex chemical compass, we have created a family of simplified, adaptable proteins-maquettes-that contain a single tryptophan residue at different distances from a covalently bound flavin. Despite the complete absence of structural resemblance to the native cryptochrome fold or sequence, the maquettes exhibit a strong magnetic field effect that rivals those observed in the natural proteins in vitro. These novel maquette designs offer unprecedented flexibility to explore the basic requirements for magnetic sensing in a protein environment.

Larger and more heterogeneous neutron star crusts: A result of strong magnetic fields

We study the effect of strong magnetic fields, of the order of ${10}^{15}--{10}^{17}$ G, on the extension of the crust of magnetized neutron stars. The dynamical instability region of neutron-proton-electron $(npe)$ matter at subsaturation densities and the mode with the largest growth rate are determined within a relativistic mean-field model. It is shown that the effect of a strong magnetic field on the instability region is very sensitive to the density dependence of the symmetry energy, and that it is at the origin of an increase of the extension of the crust and of the charge content of clusters.

Weyl fermions with arbitrary monopoles in magnetic fields: Landau levels, longitudinal magnetotransport, and density-wave ordering

We theoretically address the effects of strong magnetic fields in three-dimensional Weyl semimetals (WSMs) built out of Weyl nodes with a monopole charge $n$. For $n=1$, $2$, and $3$ we realize single, double, and triple WSM, respectively, and the monopole charge $n$ determines the integer topological invariant of the WSM. Within the linearized continuum description, the quasiparticle spectrum is then composed of Landau levels (LLs), containing exactly $n$ number of chiral zeroth Landau levels (ZLLs), irrespective of the orientation of the magnetic field. In the presence of strong backscattering, for example, (due to quenched disorder associated with random impurities), these systems generically give rise to longitudinal magnetotransport. Restricting ourselves to the quantum limit (and assuming only the subspace of the ZLLs to be partially filled) and mainly accounting for Gaussian impurities, we show that the longitudinal magnetoconductivity (LMC) in all members of the Weyl family displays a positive linear-$B$ scaling, when the field is applied along the axis that separates the Weyl nodes. But, in double and triple WSM, LMC displays a smooth crossover to a nonlinear $B$-dependence as the field is tilted away from such a high-symmetry direction. In addition, due to the enhanced density of states, the LL quantization can trigger instabilities toward the formation of translational symmetry breaking density-wave orderings for sufficiently weak interaction (BCS instability), which gaps out the ZLLs. Concomitantly as the temperature (magnetic field) is gradually decreased (increased) the LMC becomes negative. Thus WSMs with arbitrary monopole charge ($n$) can host an intriguing interplay of LL quantization, longitudinal magnetotransport (a possible manifestation of one-dimensional chiral or axial anomaly), and density-wave ordering, when placed in a strong magnetic field.

Effect of Strong Orbital Magnetic Field on the Exciton Condensation in an Extended Falicov Kimball Model

A spinless, extended Falicov-Kimball model in the presence of a perpendicular magnetic field is investigated employing a self-consistent mean-field theory in two dimensions. In the presence of the field the excitonic average Δ =< di†fi > is modified: the exciton responds in subtle different ways for different values of the magnetic flux. We examine the effects of Coulomb interaction and hybridization between the localized and itinerant electrons on the excitonic average, for rational values of the applied magnetic field. The excitonic average is found to get enhanced exponentially with the Coulomb interaction while it saturates at large hybridization. The orbital magnetic field suppresses the excitonic average in general, though a strong commensurability effect of the magnetic flux on the behaviour of the excitonic order parameter is observed.

Radial modes of slowly rotating compact stars in the presence of magnetic field

Compact stars are composed of very high-density hadron matter. When the matter is above nuclear matter density, then there is a chance of different phases of matter such as hadron matter to quark matter. There is a possible phase which, having the quark core surrounded by a mixed phase followed by hadronic matter, may be considered as a hybrid phase inside the stars called hybrid star (HS). The star which consists of only u, d and s quarks is called quark star (QS) and the star which has only hadronic matter is called neutron star (NS). For the equation of state (EOS) of hadronic matter, we have considered the Relativistic Mean Field (RMF) theory and we incorporated the effect of strong magnetic fields. For the EOS of the quark phase we use the simple MIT bag model. We have assumed Gaussian parametrization to make the density dependent for both bag pressure in quark matter and magnetic field. We have constructed the intermediate mixed phase by using the Glendenning conjecture. Eigenfrequencies of radial pulsations of slowly rotating magnetized compact stars (NS, QS, HS) are calculated in a general relativistic formalism given by Chandrasekhar and Friedman. We have studied the effect of central density on the square of the frequencies of the compact stars in the presence of zero and strong magnetic field.

Electrostatic two-stream instability in Fermi-Dirac plasmas

In this paper the electrostatic two-stream instability is investigated for a large range of plasma number-density using the quantum hydrodynamic model by incorporating the relativistic degeneracy, electron-exchange, quantum diffraction and strong parallel quantizing magnetic field effects. It is found that the electron diffraction effect significantly alters the instability growth rate in a wide range of plasma number density. Two cases of classical and quantum Landau quantization limits are compared and the parametric instability condition is closely inspected. It is remarked that for a given streaming speed the instability is bounded by an upper plasma number-density limit. It is also shown that for a given stream speed there is a maximal growth rate corresponding to specific plasma number-density and perturbation wavelength. Current study can help in better understanding of electron-beam plasma interactions and energy exchange for a wide area of number densities ranging from solid density, inertial confined plasmas, big planetary cores and compact stars. It may also be useful in understanding of electrostatic beam-plasma interactions and origin of large magnitude sustainable electrical currents in super-intense plasmas with critically high magnetic fields such as, pulsars, white dwarf interiors and neutron star crusts.

Role of nuclear physics in oscillations of magnetars

Strong magnetic fields have important effects on the crustal properties of magnetars. Here we study the magneto-elastic oscillations of magnetars taking into consideration the effect of strong magnetic fields on the crustal composition (magnetised crust). We calculate global magneto-elastic (GME) modes as well as modes confined to the crust (CME) only. The composition of the crust directly affects its shear modulus which we calculate using three different nucleon-nucleon interactions: SLy4, SkM and Sk272. The shear modulus of the crust is found to be enhanced in strong magnetic fields $\geq 10^{17}$ G for all those Skyrme interactions. It is noted that the shear modulus of the crust for the SLy4 interaction is much higher than those of the SkM and Sk272 interactions in presence of magnetic fields or not. Though we do not find any appreciable change in frequencies of fundamental GME and CME modes with and without magnetised crusts, frequencies of first overtones of CME modes are significantly affected in strong magnetic fields $\geq 10^{17}$ G. However, this feature is not observed in frequencies of first overtones of GME modes. As in earlier studies, it is also noted that the effects of crusts on frequencies of both types of maneto-elastic modes disappear when the magnetic field reaches the critical field ($B > 4 \times 10^{15}$ G). Frequencies of GME and CME modes calculated with magnetised crusts based on all three nucleon-nucleon interactions, stellar models and magnetic fields, are compared with frequencies of observed quasi-periodic oscillations (QPOS) in SGR 1806-20 and SGR1900+14. As in earlier studies, this comparison indicates that GME modes are essential to explain all the frequencies as CME modes can explain only the higher frequencies.

Properties of strongly magnetized ultradense matter and its effects on magnetar pulsations

We investigate the effect of strong magnetic fields on the adiabatic radial oscillations of hadronic stars. We describe magnetized hadronic matter within the framework of the relativistic nonlinear Walecka model and integrate the equations of relativistic radial oscillations to determine the fundamental pulsation mode. We consider that the magnetic field increases, in a density dependent way, from the surface, where it has a typical magnetar value of ${10}^{15}\phantom{\rule{4pt}{0ex}}\mathrm{G}$, to the interior of the star, where it can be as large as $3\ifmmode\times\else\texttimes\fi{}{10}^{18}\phantom{\rule{4pt}{0ex}}\mathrm{G}$. We show that magnetic fields of the order of ${10}^{18}\phantom{\rule{4pt}{0ex}}\mathrm{G}$ at the stellar core produce a significant change in the frequency of neutron star pulsations with respect to unmagnetized objects. If radial pulsations are excited in magnetar flares, they can leave an imprint in the flare lightcurves and open a new window for the study of highly magnetized ultradense matter.

De Haas-van Alphen oscillations for neutral atoms in electric fields

In this work we study the de Haas van Alfhen (dHvA) effect for neutral atoms with a nonvanishing magnetic moment interacting with an electric field. Considering the particles confined in a two dimensional (2D) atomic cloud and using the Landau-Aharonov-Casher (LAC) theory, we obtain the effective magnetic field as well as the energy eigenfunctions and eigenvalues of the system. Assuming the neutral atoms as being $ ^{87}\mathrm{Rb} $ ultracold Rydberg atoms we calculate the degeneracy of the energy levels. Under a strong effective magnetic field regime we present the quantum oscillations in the energy and effective magnetization of the atomic gas. From the dHvA period we determine the area of the Fermi circle of the atomic cloud.

The influence of Marangoni effect on flow and deformation of an electromagnetically levitated molten droplet under static magnetic fields

The influence of Marangoni effect on electromagnetically levitated molten droplet under a static magnetic field is investigated by a series of numerical simulations based on Arbitrary Lagrangian–Eulerian method. Firstly the motions and dynamic deformation as well as flow and temperature fields of droplet without Marangoni effect are calculated under various static magnetic fields, then Marangoni effect is introduced and clear comparisons are conducted. The results show that the static magnetic field could dynamically suppress the oscillation and enhance the levitation stability of molten droplet. With the increase of magnetic field intensity, the oscillation amplitude of droplet is decreased and the dynamic deformation during the oscillation is reduced. When the droplet eventually achieves the equilibrium position, the deformation can also be reduced by static magnetic field. Meanwhile the convection inside molten droplet is suppressed and the temperature difference grows, creating a suiting situation for Marangoni effect. The influence of Marangoni effect on behaviors of molten droplet can be divided into two aspects. On one hand, when the static magnetic field is less than 2T, considering of Marangoni effect will dynamically enlarge the deformation due to the linear decrease of surface tension. But further increasing of magnetic field, the shape difference between cases with and without Marangoni effect gets minished gradually because of the strong suppression effect of magnetic field on droplet deformation. On the other hand, when static magnetic field is over 2T, the Marangoni effect would produce a new vortex near the equatorial surface of droplet. With the increasing of magnetic field, firstly the maximum velocity area shifts into zones near the free surface due to the competition between electromagnetic force and thermocapillary force. Then it returns to the free surface and on this occasion, the flow near the equatorial areas is totally dominated by thermocapillary force. Undoubtedly, the Marangoni effect plays an important role in electromagnetic levitation process and it is necessary to take the Marangoni effect into consideration in future numerical simulations for precise prediction of droplet behavior.

TH-CD-BRA-04: Effect of a Strong Magnetic Field On TLDs, OSLDs, and Gafchromic Films Using An Electromagnet

Purpose: To study the effect of strong magnetic field on three types of dosimeters using an electromagnet inside a Linac vault. Materials and Methods: Three types of dosimeters, thermoluminescent Dosimeters (TLDs), optically stimulated luminescent Dosimeters (OSLDs), and EBT3 Film were used to measure radiation dose response inside an electromagnet that could produce a strong magnetic field (B>1.5 T). The dosimeters were placed inside a plastic phantom between the two poles of the magnet, at approximately 3 meters from the iso-center of an Elekta Versa HD Linac. The B field was calibrated with a Gauss meter (Model: GM-2, AlphaLab Inc). The dosimeters received ∼2 Gy with and without the presence of the 1.5 T magnetic field. The EBT3 films were scanned 24 hours before and 24 hours after irradiation. The TLD dosimeters were read 1 week after irradiation. The OSLDs were read two weeks after irradiation. The ratios of signals of dosimeters irradiated with the B field to the signals without the B field were calculated. Two experiments have been conducted so far. Results: The ratios (averaged over two experiments) of dosimeter signals with vs without B field were 0.994 for films, 0.994 for OSLDs, and 1.002 for TLDs. The statistical uncertainty was ∼3%. Conclusions: The three types of dosimeters (film, TLD, OSLD) seem not affected by the presence of a magnetic field (B=1.5 T) with the uncertainty of ∼3%. They may be suitable for QA purposes in a strong B field up to 1.5 T. More measurements will be conducted for reproducibility testing. We acknowledge research support from Elekta AB.

Saturation properties of nuclear matter in the presence of strong magnetic field

Different saturation properties of cold symmetric nuclear matter in the strong magnetic field have been considered. We have seen that for magnetic fields about $B> 3 \times 10 ^ {17}\ G$, {for both cases with and without nucleon anomalous magnetic moments}, the saturation density and saturation energy grow by increasing the magnetic field. It is indicated that the magnetic susceptibility of symmetric nuclear matter becomes negative showing the diamagnetic response especially at $B< 3 \times 10 ^ {17}\ G$. We have found that for the nuclear matter, the magnitude of orbital magnetization reaches the higher values comparing to the spin magnetization. Our results for the incompressibility show that at high enough magnetic fields, i.e. $B> 3 \times 10 ^ {17}\ G$, {the softening of equation of state caused by Landau quantization is overwhelmed by stiffening due to the magnetization of nuclear matter.} We have shown that the effects of strong magnetic field on nuclear matter may affect the constraints on the equation of state of symmetric nuclear matter obtained applying the experimental observable.

Solar r-process-constrained actinide production in neutrino-driven winds of supernovae

Long-lived radioactive nuclei play an important role as nucleo-cosmochronometers and as cosmic tracers of nucleosynthetic source activity. In particular nuclei in the actinide region like thorium, uranium, and plutonium can testify to the enrichment of an environment by the still enigmatic astrophysical sources that are responsible for the production of neutron-rich nuclei by the rapid neutron-capture process (r-process). Supernovae and merging neutron-star (NS) or NS-black hole binaries are considered as most likely sources of the r-nuclei. But arguments in favour of one or the other or both are indirect and make use of assumptions; they are based on theoretical models with remaining simplifications and shortcomings. An unambiguous observational determination of a production event is still missing. In order to facilitate searches in this direction, e.g.\ by looking for radioactive tracers in stellar envelopes, the interstellar medium or terrestrial reservoirs, we provide improved theoretical estimates and corresponding uncertainty ranges for the actinide production ($^{232}$Th, $^{235,236,238}$U, $^{237}$Np, $^{244}$Pu, and $^{247}$Cm) in neutrino-driven winds of core-collapse supernovae. Since state-of-the-art supernova models do not yield r-process viable conditions ---but still lack, for example, the effects of strong magnetic fields--- we base our investigation on a simple analytical, Newtonian, adiabatic and steady-state wind model and consider the superposition of a large number of contributing components, whose nucleosynthesis-relevant parameters (mass weight, entropy, expansion time scale, and neutron excess) are constrained by the assumption that the integrated wind nucleosynthesis closely reproduces the solar system distribution of r-process elements. We also test the influence of uncertain nuclear physics.

Orbital effects of strong magnetic field on a two-dimensional Holstein polaron

We investigate the orbital effects of strong external magnetic field on the ground state properties of a two dimensional holstein polaron, employing variational approaches based on the exact diagonalization (VAED). From the ground state energy and the wave function we calculate electron-phonon correlation function, the average phonon number and the Drude weight and investigate the evolution of a 2D holstein polaron as a function of the magnetic flux. Although the external magnetic field affects the polaron throughout the parameter regime, we show that the magnetic field has a stronger effect on a loosely bound (spatially extended) polaron. We also find that the magnetic field can be used as a tuning parameter, particularly for weakly coupled polaron, to reduce the spatial extent of a large polaron.

Simulation of Switching Arcs Under Transverse Magnetic Fields for DC Interruption

The importance of low-voltage devices to interrupt dc currents under load and fault conditions has been considerably growing recently. From experimental work, it is known that arcs in strong transverse magnetic fields are able to generate arc voltages high enough to interrupt such circuits. To study the mechanisms behind this process, 2-D simulations of the plasma fluid flow in arc chambers, coupled with current flow and magnetic field, were carried out with a Multiphysics FEM program. For arc chambers, where the arc is pressed against a wall, it could be shown that the power removal that determines directly the arc voltage per unit length occurs predominantly by convection in the $J\times B$ force field (electromagnetic pump). In this sense, hydrogen is much more effective than air. In a similar way, this mechanism can also explain the effect of strong magnetic blow fields in arcs with free environment.

Effect of strong magnetic fields on gas adsorption

The effect of strong pulsed magnetic fields on gas adsorption at dielectric surfaces is demonstrated. We describe the experimental technique and the results indicating a considerable increase in the surface concentration of the adsorbed substance under the action of pulsed magnetic fields with an induction amplitude up to 50 T. The increase in the lifetime and stability of the adsorbed layer is observed. It is shown that the effect of magnetically induced sorption is also manifested in the interaction of iodine vapor with the surface of dielectrics.