Magnetic Quantization Research Articles

A note on the geometry of hypermultiplets in the field theory of intersecting D3-branes

We study the Kähler geometry of the hypermultiplet moduli space in the effective field theory of two intersecting D3-branes from the viewpoint of the classical RG flow equation governing the running of the Kähler potential defining the theory. We analyze this equation as a nonlinear PDE of first order and construct a general class of its solutions compatible with the symmetries in the problem. These solutions involve an arbitrary function of two independent variables and generically break the N=2 supersymmetry of the system to N=1 in 4 dimensions. Restricting this general class by the constraints of N=2 supersymmetry and periodicity for magnetic charge quantization, we recover the Gibbons-Hawking geometry previously proposed for this system in ref. [5]. This provides a systematic derivation and a uniqueness proof for the geometry of the moduli space in this problem. We also give an independent proof of the preservation of the N=2 supersymmetry by the RG flow and a reinterpretation of the periodicity in terms of a symmetry of the RG flow equation in appendices.

Magnetoacoustics and magnetic quantization of Fermi states in relativistic plasmas

Abstract Dispersive characteristics of electromagnetic sound waves with frequencies less than the electron and ion gyro-frequencies are studied herein analytically and numerically at astrophysical scales. Magnetic quantization of Fermi states is concerned with the degenerate relativistic electrons fluid treated by quantum hydrodynamic model (QHD). The quantum features are included from Landau quantized Fermi pressure dependent upon the dc magnetic field, whereas the ions are treated as nondegenerate and classical. The numerical analysis verifies the analytical results. The phase speed of magnetosonic waves for relativistic degenerate plasma typically for white dwarf stars parameters is depicted from the graphical figures. In this manuscript, an overlooked feature of quantization, that is Landau quantization, is mainly focused for magnetoacoustics in plasmas.

Optical properties and Landau quantisations in twisted bilayer graphene

ABSTRACT The optical properties and Landau quantisations in twisted bilayer graphene are investigated using a generalised tight-binding model that takes into account all interlayer and intralayer atomic interactions in the Moire superlattice. The system is a zero-gap semiconductor with double-degenerate Dirac-cone structures, and saddle-point energy dispersions appear at low energies for small twisting angles. The magnetic quantisation phenomena in this system are rich and unique, with Landau-level subgroups specified owing to specific Moire zone folding through modulation of the stacking angles. The Landau-level spectrum shows hybridised characteristics associated with those in monolayer, as well as AA and AB stackings. The detailed analysis explores the complex relations among the different sublattices on the same and different graphene layers.

Квазиклассическое квантовое обобщение уравнений Лондонов и гипотеза монополей

The paper considers the London equation semi-classical generalization leading to a connection between the Cooper pairs magnetic flux quantization and the electric charge discreteness. Using the Bohr --- Sommerfeld quantization rule, a derivation of the magnetic flux quantization was made on the basis of the fluxoid uniqueness. The resulting quantization was applied to the magnetic monopoles hypothesis proposed by Dirac, which remains relevant due to the asymmetry present in the modern physics in describing electrical and magnetic properties of matter. On a fairly simple model of the possible experiment, an option of registering a monopole by a jump in the magnetic induction flux and the associated alteration in the circuit current were studied. The paper analyzed the problems of the monopole different measurement units and the results similar to those obtained on the basis of the Schwinger series of works, where he proceeded from considering introduction of a hypothetical particle with the electric and magnetic charges, i.e., the dyon. Possible explanation of the Abrikosov vortex is presented, it is based on vortex representation in the form of a magnetized thin thread through the magnetic tubes, at the ends of which monopoles of different charges (dipole) are positioned. Unlike most the works devoted to this problem, calculations were performed in the SI system. The monopole quantization conditions were derived

Effect of chirality imbalance on Hall transport ofPrRhC2

Much has been learned about the topological transport in real materials. We investigate the interplay between magnetism and topology in the magneto-transport of PrRhC$_2$. The four-fold degeneracy reduces to two-fold followed by non-degenerate Weyl nodes when the orientation of the magnetic quantization axis is changed from easy axis to body-diagonal through face-diagonal. This engenders chirality imbalance between positive and negative chirality Weyl nodes around the Fermi energy. We observe a significant enhancement in the chiral anomaly mediated response such as planar Hall conductivity and longitudinal magneto-conductivity, due to the emergence of chirality imbalance upon orienting the magnetic quantization axis to body-diagonal. The angular variations of the above quantities for different magnetic quantization axis clearly refer to the typical signature of planar Hall effect in Weyl semimetals. We further investigate the profiles of anomalous Hall conductivities as a function of Fermi energy to explore the effects of symmetries as well as chirality imbalance on Berry curvature.

On the Einstein relation between mobility and diffusion cofficint in an active Nanostructured Materials

It is commonly known that the speed at which contemporary switching semiconductors work much depends on the carrier degeneracy of the band. Furthermore, the relation of the diffusivity to mobility ratio of the carriers in semiconductors (referred to as DMR) is very helpful because it is more accurate than any of the individual relations for diffusivity to mobility ratio, which is thought to be the two most frequently used parameters in carrier transport in semiconductors. With n-InSb and Hg1-xCdxTe as examples of numerical calculations, we will examine DMR under strong magnetic quantization of III-V in line with the three- and two-band models of Kane, respectively, along with parabolic energy bands.

On magnetic monopole and Dirac quantization condition in the minimal length formalism

In this article, we study the effects of minimal length corrections on the cyclotron acceleration and radiation of a charged particle moving in a magnetic monopole field. Using the modified Hamiltonian describing the dynamics of a charged particle moving in a magnetic monopole field, we derive the modified cyclotron frequency and modified acceleration. Also, we derive the modified power for the cyclotron radiation using the modified acceleration. We find that all modified quantities are dependent on the deformation parameter α. In addition, we find that the modified electromagnetic angular momentum and magnetic charges are not quantized as an integer multiple; thus, we establish that the modified Dirac quantization condition and the usual Dirac quantization condition is just the term of zero order in α. The modified Dirac quantization condition allows fractional charges that arise from vacuum fluctuations. In the Born approximation, we derive the modified scattering cross-section and then we estimate the upper bound on the minimal length.

Generalized Peierls substitution for the tight-binding model of twisted graphene systems in a magnetic field

This work aims at addressing an important advanced methodology for twisted graphene in the presence of applied magnetic field, which is the Bloch-basis tight-binding model (TBM) in conjunction with the generalized Peierls substitution. We investigate extensively the band structures, Landau levels (LLs), and quantum Hall conductivity (QHC) of twisted bilayer graphene and twisted double-bilayer graphene, as well as their dependence on the twist angle. Comparison between these crucial properties of monolayer graphene, Bernal bilayer graphene, and the twisted systems is carefully made to highlight the roles played by twisting. The unique selection rules of inter-LL transition, which is crucial for achieving a deep understanding of the step structures of QHC, are identified through the properties of LL wave functions. The effective TBM is combined with the generalized Peierls substitution to investigate the magnetic quantization of twisted graphene systems at magic angle. Our theoretical model opens up an opportunity for comprehension of the interplay between an applied magnetic field and the twisting effect associated with layered graphene. The proposed method is expected to be applicable for the calculation of magnetic quantization problems of other complex systems.

Extremely long-range, high-temperature Josephson coupling across a half-metallic ferromagnet.

The Josephson effect results from the coupling of two superconductors across a spacer such as an insulator, a normal metal or a ferromagnet to yield a phase coherent quantum state. However, in junctions with ferromagnetic spacers, very long-range Josephson effects have remained elusive. Here we demonstrate extremely long-range (micrometric) high-temperature (tens of kelvins) Josephson coupling across the half-metallic manganite La0.7Sr0.3MnO3 combined with the superconducting cuprate YBa2Cu3O7. These planar junctions, in addition to large critical currents, display the hallmarks of Josephson physics, such as critical current oscillations driven by magnetic flux quantization and quantum phase locking effects under microwave excitation (Shapiro steps). The latter display an anomalous doubling of the Josephson frequency predicted by several theories. In addition to its fundamental interest, the marriage between high-temperature, dissipationless quantum coherent transport and full spin polarization brings opportunities for the practical realization of superconducting spintronics, and opens new perspectives for quantum computing.

The Magneto Electron Statistics in Heavily Doped N Type-Intrinsic-P Type-Intrinsic Structures.

In this paper we study the Electron Statistics in Heavily Doped N Type-Intrinsic-P Type-Intrinsic structures of non-linear optical, tetragonal and opto-electronic materials in the presence of magnetic quantization. It is found taking such heavily doped structures of Cd₃As₂, CdGeAs₂, InAs, InSb, Hg1-xCdxTe, In1-xGaxAsyP1-y as examples that the Fermi energy (EF) oscillates with inverse quantizing magnetic field (1/B) and increases with increasing electron concentration with different numerical magnitudes which is the signature of respective band structure. The numerical value of the Fermi energy is different in different cases due to the different values of the energy band constants.

Superconducting Circuits without Inductors Based on Bistable Josephson Junctions

Magnetic flux quantization in superconductors allows the implementation of fast and energy-efficient digital superconducting circuits. However, the information representation in magnetic flux severely limits their functional density presenting a long-standing problem. Here we introduce a concept of superconducting digital circuits that do not utilize magnetic flux and have no inductors. We argue that neither the use of geometrical nor kinetic inductance is promising for the deep scaling of superconducting circuits. The key idea of our approach is the utilization of bistable Josephson junctions allowing the representation of information in their Josephson energy. Since the proposed circuits are composed of Josephson junctions only, they can be called all-Josephson junction (all-JJ) circuits. We present a methodology for the design of the circuits consisting of conventional and bistable junctions. We analyze the principles of the circuit functioning, ranging from simple logic cells and ending with an 8-bit parallel adder. The utilization of bistable junctions in the all-JJ circuits is promising in the aspects of simplification of schematics and the decrease of the JJ count leading to space-efficiency.

Wave propagation with degenerate electron–positron in magnetically quantised ion beam plasma

In an ion beam plasma system, the effect of magnetically quantised degenerate trapped electron and positron, on small-amplitude ion-acoustic solitary waves are studied with the help of Korteweg–de Vries (KdV) equation. Here the magnetised positive ions and beam ions are considered as non-degenerate. The effect of magnetic quantisation, degenerate temperature, normalised positron concentration, normalised ion beam concentration along with other relevant physical plasma parameters of the origin of astrophysical plasma environment, on solitary wave propagation is studied especially in the nonlinear regime. On the other hand, in the linear regime, the dependency of frequency and wavenumber on the aforementioned plasma parameters are discussed. It is found that both compressive and rarefactive type solitary waves can exist in such a plasma environment. Three different modes of propagation, the fast beam and slow beam modes and the inherent ion-acoustic mode coexist in such plasma systems and the role of different degenerate plasma parameters on these wave modes are also discussed in detail. The normalised positron concentration and velocity, as well as the normalised ion beam concentration along with different degenerate plasma parameters, has an astounding control on the amount of compression and rarefaction, a typical plasma wave mode is supposed to undergo. Within the chosen degenerate and non-degenerate plasma parameters, for a compressive (rarefactive) fast beam mode, the slow mode appears as rarefactive (compressive). For some typical combinations of degenerate parameters, the fast mode can propagate with a hypersonic phase velocity which shows distinctive characteristics with positron density.

Landau quantized dynamics and spectrum of the diced lattice

In this work the role of magnetic Landau quantization in the dynamics and spectrum of diced lattice charge carriers is studied in terms of the associated pseudospin 1 Green’s function. The equations of motion for the 9 matrix elements of this Green’s function are formulated in position/frequency representation and are solved explicitly in terms of a closed form integral representation involving only elementary functions. The latter is subsequently expanded in a Laguerre eigenfunction series whose frequency poles identify the discretized energy spectrum for the Landau-quantized diced lattice as ( is the characteristic speed for the diced lattice) which differs significantly from the nonrelativistic linear dependence of ϵ n on B, and is similar to the corresponding dependence of other Dirac materials (graphene, group VI dichalcogenides).

Magnetic susceptibility of QCD matter and its decomposition from the lattice

We determine the magnetic susceptibility of thermal QCD matter by means of first principles lattice simulations using staggered quarks with physical masses. A novel method is employed that only requires simulations at zero background field, thereby circumventing problems related to magnetic flux quantization. After a careful continuum limit extrapolation, diamagnetic behavior (negative susceptibility) is found at low temperatures and strong paramagnetism (positive susceptibility) at high temperatures. We revisit the decomposition of the magnetic susceptibility into spin- and orbital angular momentum- related contributions. The spin term — related to the normalization of the photon lightcone distribution amplitude at zero temperature — is calculated non-perturbatively and extrapolated to the continuum limit. Having access to both the full magnetic susceptibility and the spin term, we calculate the orbital angular momentum contribution for the first time. The results reveal the opposite of what might be expected based on a free fermion picture. We provide a simple parametrization of the temperature- and magnetic field-dependence of the QCD equation of state that can be used in phenomenological studies.

Spin-Triplet Pairing State Evidenced by Half-Quantum Flux in a Noncentrosymmetric Superconductor.

A prime category of superconducting materials in which to look for spin-triplet pairing and topological superconductivity are superconductors without inversion symmetry. It is predicted that the broken parity symmetry gives rise to an admixture of spin-triplet and spin-singlet pairing states. However, experimental confirmation of pairing mixing in any material remains elusive. In this work, we perform a phase-sensitive experiment to examine the pairing state of noncentrosymmetric superconductor α-BiPd. The Little-Parks effect observed in mesoscopic polycrystalline α-BiPd rings reveals the presence of half-integer magnetic flux quantization, which provides a decisive evidence for the spin-triplet pairing state. We find both half-quantum fluxes and integer-quantum fluxes of different proportions, consistent with the scenario of an admixture of singlet-triplet pairing.

Magnetic field quantization in pulsars

Magnetic field quantization is an important issue for degenerate environments such as neutron stars, radio pulsars and magnetars etc., due to the fact that these stars have a magnetic field higher than the quantum critical field strength of the order of $4.4\times 10^{13}~\text{G}$ , accordingly, the cyclotron energy may be equal to or even much more than the Fermi energy of degenerate particles. We shall formulate here the exotic physics of strongly magnetized neutron stars, known as pulsars, specifically focusing on the outcomes of the quantized magnetic pressure. In this scenario, while following the modified quantum hydrodynamic model, we shall investigate both linear and nonlinear fast magnetosonic waves in a strongly magnetized, weakly ionized degenerate plasma consisting of neutrons and an electron–ion plasma in the atmosphere of a pulsar. Here, linear analysis depicts that sufficiently long, fast magnetosonic waves may exist in a weakly dispersive pulsar having finite phase speed at cutoff. To investigate one-dimensional nonlinear fast magnetosonic waves, a neutron density expression as a function of both the electron magnetic and neutron degenerate pressures, is derived with the aid of Riemann’s wave solution. Consequently, a modified Korteweg–de Vries equation is derived, having a rarefractive solitary wave solution. It is found that the basic properties such as amplitude, width and phase speed of the fast magnetoacoustic waves are significantly altered by the electron magnetic and the neutron degenerate pressures. The results of this theoretical investigation may be useful for understanding the formation and features of the solitary structures in astrophysical compact objects such as pulsars, magnetars and white dwarfs etc.

Landau quantization effects on hybrid waves in semiconductor plasmas

The impact of Landau quantization on the lower hybrid waves (LHWs) exciting in the semiconductor plasmas, due to classical electron beam, is studied. The quantum hydrodynamic model is employed to derive the dispersion relation of low-frequency electrostatic waves for instability analysis of the LHWs. The quantum effects include Fermi degenerate pressure, Bohm potential, Landau quantization, and exchange-correlation potential for semiconductor plasma species. The dispersion relation is elaborated both quantitatively and qualitatively for the special case of GaAs in the presence of external magnetic field $$\mathbf{B}_0$$. The impact of different plasma parameters such as density ratios of electrons and holes $$\alpha $$, beam temperature $$T_{\mathrm{b}}$$, speed of beam electrons $$v_0$$, propagation angle $$\theta $$, cyclotron frequency $$\omega _{\mathrm{ce}}$$, temperature of electrons and holes $$T_{\mathrm{e}}$$, $$T_{\mathrm{h}}$$ and Landau quantization $$\eta $$, on the dispersion relation of LHWs, is studied. The instability of the LHWs remarkably increases by increasing the concentration of the semiconductor electrons, propagation angle of the wave vector and the beam speed, for the magnetic quantization parameter. However, the instability decreases by increasing the temperature of beam. It is noticed that at $$(T_{\mathrm{b}}>v_0)$$, the $$\eta $$ has no effect on the instability.

Giant fractional Shapiro steps in anisotropic Josephson junction arrays

Giant fractional Shapiro steps have been observed in Josephson junction arrays as resulting from magnetic flux quantization in the two-dimensional array. We demonstrate experimentally the appearance of giant fractional Shapiro steps in anisotropic Josephson junction arrays as unambiguous evidence of a skewed current phase relationship. Introducing anisotropy in the array results in a giant collective high frequency response that reflects the properties of a single junction, as evidenced by the observation of a Fraunhofer like magnetic field dependence of the total critical current of the system. The observed phase dynamics can be perfectly captured within an extended resistively shunted Josephson junction model. These results directly indicate the potential of Josephson junction arrays to explore the current phase relation in a very broad frequency range (down to 50 MHz) and in a wide variety of novel link materials exhibiting non-conventional current phase relationships.

Solitary Wave with Quantisation of Electron’s Orbit in a Magnetised Plasma in the Presence of Heavy Negative Ions

Abstract The propagation characteristics of solitary wave in a degenerate plasma in the presence of Landau-quantised magnetic field and heavy negative ion are studied. The nature of solitary wave in such plasma under the influence of magnetic quantisation and the concentration of both electrons and negative ions, as well as in the presence of degenerate temperature, are studied with the help of a time-independent analytical scheme of the solution of Zakharov–Kuznetsov equation. The electron density, as well as the magnetic quantisation parameter, has an outstanding effect on the features of solitary wave proliferation in such plasma. Interestingly, for any fixed electron density, the magnetic quantisation parameter has an equal control on the maximum height and dispersive properties of the solitary wave. Toward higher temperatures and higher magnetic fields, the width of the solitary wave decreases. For a lower magnetic field, the maximum amplitude of the solitary wave decreases rapidly at higher values of degenerate temperature and negative ion concentration; however, at a lower value of degenerate temperature, the maximum amplitude increases with increasing negative ion concentration.

Supersonic Shock Wave with Landau Quantization in a Relativistic Degenerate Plasma**Supported by Manoj Kumar Deka from DST-SERB of India under Grant No YSS/2015/001896.

A three-dimensional (3D) Burgers’ equation adopting perturbative methodology is derived to study the evolution of a shock wave with Landau quantized magnetic field in relativistic quantum plasma. The characteristics of a shock wave in such a plasma under the influence of magnetic quantization, relativistic parameter and degenerate electron density are studied with assistance of steady state solution. The magnetic field has a noteworthy control, especially on the shock wave’s amplitude in the lower range of the electron density, whereas the amplitude in the higher range of the electron density reduces remarkably. The rate of increase of shock wave potential is much higher (lower) with a magnetic field in the lower (higher) range of electron density. With the relativistic factor, the shock wave’s amplitude increases significantly and the rate of increase is higher (lower) for lower (higher) electron density. The combined effect of the increase of relativistic factor and the magnetic field on the strength of the shock wave, results in the highest value of the wave potential in the lower range of the degenerate electron density.