Effective Ru moment in RuSr2Eu2−xCexCu2O10 from high-temperature magnetic susceptibility

We have made high-temperature (250 K<T<800 K) DC susceptibility measurements in the compounds RuSr₂Eu_2−xCe_xCu₂O₁₀ for x=0.6,0.8, and 1.0 in order to determine the Ru effective magnetic moment. After carefully subtracting all contributions to the magnetic susceptibility except that of the Ru ions, we have been able to fit the Ru susceptibility with a law χ_Ru=χ₀+C_Ru/(T−Θ_Ru). We have found that the Ru effective moment falls between the values expected for Ru⁵⁺ in spin states and . We have also found a dependence of μ_eff(Ru) and Θ_Ru with the Ce content x.     

The two-dimensional D complex in intense AC and strong magnetic fields

The combined effect of intense time dependent far infrared field (FIR) and a strong static magnetic field on interacting electrons in a two-dimensional complex is studied. The two-electron problem is cast in the language of the Center of Mass (CM) and relative particles, which in turn is mapped into a problem of coupled nonlinear harmonic oscillators. The time evolution of the CM and its coupling to the internal degrees of freedom via the coulomb interaction and the Pauli exclusion principle is investigated.     

Effective supersymmetric theory and muon anomalous magnetic moment with R parity violation

The effective supersymmetric theory (ESUSY) with R parity conservation cannot give a large anomalous magnetic moment of μ. It is pointed out that the flavor conservation and a large (g−2)_μ within the experimental limits are achievable in the ESUSY with R parity violating couplings involving the third generation superparticles.     

Critical properties of XY model dimensional layered magnetic on two- films

Using Monte Carlo simulations, we have investigated the classical $XY$ model on triangular lattices of ultra-thin film structures with middle ferromagnetic layers sandwiched between two antiferromagnetic layers. The internal energy, the specific heat, the chirality and the chiral susceptibility are calculated in order to clarify phase transitions and critical phenomena. From the finite-size scaling analyses, the values of critical exponents are determined. In a range of interaction parameters, we find that the chirality steeply goes up as temperature increases in a temperature range; correspondingly the value of a critical exponent for this change is estimated.     

电矩张量与旋转带电体的磁矩

基于旋转带电体的磁矩与刚体转动惯量之间的类比关系,引入带电体的一个不同于电四极矩的电矩张量的概念,进而引入标量电矩二次曲面及电矩主轴的概念,借助正交变换及电矩张量矩阵的本征值理论,推导出沿任意方向定轴旋转带电体的磁矩的计算公式及电矩张量的若干性质,并举例说明.     

Magnetic correction to the anomalous magnetic moment of electrons

We investigate the leading order correction of anomalous magnetic moment (AMM) to electrons in a weak magnetic field and find that the magnetic correction is negative and magnetic field dependent, indicating a magnetic catalysis effect for the electron gas. In the laboratory, to measure the g − 2, the magnitude of the magnetic field B is several T, and correspondingly the magnetic correction to the AMM of electron/muon is around 10⁻³⁴/10⁻⁴², therefore the magnetic correction can be safely neglected in the current measurement. However, when the magnitude of the magnetic field strength is comparable with the electron mass, the magnetic correction of the electron's AMM will become considerable. This general magnetic correction to the charged fermion's AMM can be extended to study quantum chromodynamic matter under a strong magnetic field.     

The anomalous magnetic moment of the electron

The value of the electron's magnetic moment is a fundamental quantity in physics. Its deviation from the value expected from Dirac theory has given enormous impetus to the field of quantum theory and especially to quantum electrodynamics (QED) as the relativistic quantum field theory of electrodynamics. In fact, the measured values both for free and for bound electrons are explained by corresponding QED calculations on the part per trillion and part per billion level of accuracy, respectively. This agreement is amongst the best known in physics today. In turn, it allows highly precise determinations of related fundamental constants like the fine structure constant α or the electron mass. The present article discusses the application of the continuous Stern–Gerlach effect to the precise measurement of magnetic moments, especially of the electron bound in highly charged ions and possible tests of calculations in the framework of QED of bound states. Also, a test of QED in a more general approach by the comparison of values for the fine structure constant derived from different measurements, will be discussed.     

On the interpretation of the electron anomalous magnetic moment

Guided by a Compton-sized model, we demonstrate that: (a) the magnetic self-energy of the electron, as estimated initially by Rasetti and Fermi, can be directly related to both the sign and the magnitude of the electron anomalous magnetic moment; and (b) the classical expression for the magnetic self-energy of the electron exhibits the same characteristic logarithmic divergence that occurs in QED. This electron model quantitatively reproduces the spin, magnetic moment, and gyromagnetic ratio of the electron, correct to first order in = e² /c. It also relates the quantum-mechanical spin projection angle to the vanishing of the electric quadrupole moment, and it is capable of reproducing point-like scattering behavior.     

A method based on magnetic moment measurement to identify the structural transition of quenched Fe1 -xGax (x = 0.15ben 0.30) alloys

A method based on the measurement of Fe average atomic magnetic moment to identify the structural transition caused by the increase of Ga content in quenched Fe_{1 - x}Ga_x alloys (0.15 ≤ x ≤ 0.30) is proposed. The quenched Fe_{1 - x}Ga_x alloys show a change of the Fe average atomic magnetic moment from 2.25 μ_B to 1.78 μ_B and then to 1.58 μ_B, which corresponds to the structural transition from A2 to D0₃ and then to B2. The relationship between the structure and the magnetostriction is clarified, and the maximum magnetostriction appears in the A2 phase. The variation tendency of the magnetostriction is well characterized, which also reflects the structural transition.     

Hall resistance and the diamagnetic moment of periodically modulated two-dimensional systems

It is argued that the Hall resistance of macroscopic samples can be directly obtained by ensemble averaged transport properties of mesoscopic systems. The resulting formula relates the Hall current to the part of the magnetic moment of Fermi electrons, which originates in macroscopic currents only. As one of the possible application the Hall resistance of the periodically modulated two-dimensional electron system in the strong magnetic field is briefly discussed.     

Magnetic moment predictions of odd-A nuclei with the Bayesian neural network approach

The Bayesian neural network approach has been employed to improve the nuclear magnetic moment predictions of odd-A nuclei. The Schmidt magnetic moment obtained from the extreme single-particle shell model makes large root-mean-square (rms) deviations from data, i.e., 0.949 \begin{document}$ \mu_\mathrm{N} $\end{document} and 1.272 \begin{document}$ \mu_\mathrm{N} $\end{document} for odd-neutron nuclei and odd-proton nuclei, respectively. By including the dependence of the nuclear spin and Schmidt magnetic moment, the machine-learning approach precisely describes the magnetic moments of odd-A nuclei with rms deviations of 0.036 \begin{document}$ \mu_\mathrm{N} $\end{document} for odd-neutron nuclei and 0.061 \begin{document}$ \mu_\mathrm{N} $\end{document} for odd-proton nuclei. Furthermore, the evolution of magnetic moments along isotopic chains, including the staggering and sudden jump trend, which are difficult to describe using nuclear models, have been well reproduced by the Bayesian neural network (BNN) approach. The magnetic moments of doubly closed-shell \begin{document}$ \pm1 $\end{document} nuclei, for example, isoscalar and isovector magnetic moments, have been well studied and compared with the corresponding non-relativistic and relativistic calculations.     

A simple method to estimate the magnetic moment of magnetic micro-particles

Micro-particles in suspension in a fluid are an example of a very low Reynolds number problem. In this case, no inertial effects are observed. Magnetic micro-particles with magnetic moment m, suspended in a fluid orient to applied external magnetic fields B due to the interaction between the field and the magnetic moment. In this work, we present a simple method to estimate the total magnetic moment of magnetic micro-organisms. The method is based on the application of an external oscillating magnetic field in the sites where the micro-organisms are. In this case, it is possible to obtain theoretically the solution of the equation of motion (rotation of the organism and its trajectory). The solution is a transcendental equation relating the orientation angle and m and can be solved by numerical methods. Changing the frequency and/or the field intensity, it is possible to obtain a situation in which the crystal rotates uninterruptedly (a resonance regime). This condition is related to the applied field intensity, to the frequency, to the medium viscosity, to the crystal dimension, and to the micro-crystal magnetic moment m. The method can be used to estimate the total cellular magnetic moment of magnetic micro-particles.     

Majorana neutrino transition magnetic moment in a variant of Zee model with horizontal symmetry

A SU(2) _H symmetric variant of Zee model of lepton flavor violation is presented and is shown to lead to neutrino transition magnetic moment of the order required to explain the solar neutrino deficit and the possible anticorrelation of solar neutrino flux with sunspot activity via VVO mechanism. The use of horizontal symmetry leads to totally degenerate neutrino states which may be combined to form a ZKM Dirac neutrino with naturally small mass.     

Valley filtering due to orbital magnetic moment in bilayer graphene

We investigate the effect of valley-dependent orbital magnetic moment on the transmission of quasiparticles through biased bilayer graphene npn and pnp junctions in the presence of out-of-plane magnetic field. It is shown that the valley-polarized Zeeman-like energy splitting, due to the interaction of orbital magnetic moment with magnetic field, can suppress the transmission of quasiparticles of one valley while transmitting those of the other valley. This valley-selective transmission property can be exploited for valley filtering. We demonstrate that the npn and pnp junction, respectively, filters off the $K^{\prime }$-valley and K-valley particles, with nearly perfect degree of filtration.     

Dynamical spin susceptibility of the d–p model in the over doping region

Dynamical spin susceptibility χ^s(q,ω) of the d–p model in the over doping region is investigated by using the auxiliary boson technique. It includes higher order terms of the 1/N-expansion within the random phase approximation (RPA) of the local vertex, where frequency dependence of the quasi-particle interaction is taken into account. The incommensurate spin fluctuation is obtained due to the nesting effect in the low energy region (ωω^*), whereas the commensurate one in the high energy region (ωω^*), the characteristic energy ω^* is estimated to be about 30 meV. Both of the spin–lattice relaxation rate 1/T₁ and the spin–spin relaxation rate 1/T_g monotonically increase as T decreases, while the spin Knight shift K is almost independent of T.     

Two-loop Majorana neutrino mass and magnetic moment in a gauge model

Two-loop contributions to Majorana mass and transition magnetic moment in a gauge model not in conflict with decaying neutrino dark matter (DDM) hypothesis have been studied. Another variant of an earlier model [J Dhar and S Dev,Pramana — J. Phys. 39 541 (1992)] consistent with the DDM hypothesis is proposed and is shown to lead to large enough neutrino magnetic moment and consistent with the phenomenological constraints on neutrino mass.     

Magnetic moment of phonons in graphene induced by a magnetic field

A magnetic field not only changes the electronic structure in graphene but also affects the phonon excitations via the electron-phonon interaction and even enables the phonons to generate magnetism. In this paper, we evaluate the magnetic moment of phonons in graphene using a generating-functional technique. The calculation results indicate that the phonon magnetic moment exists only in a weak magnetic field. The step-like change of the magnetic moment with the magnetic field reflects a macroscopic quantum effect.     

缪轻子反常磁矩和北京谱仪实验

最新的缪子反常磁矩实验测量结果与标准模型理论预言偏离4.2σ,提供了新物理存在的重要证据。然而要确认新物理的存在,实验和理论还需要进一步提高精度。运行在量子色动力学微扰与非微扰过渡能区的北京谱仪实验能够约束缪子反常磁矩理论计算中最重要的误差来源——强相互作用的修正。文章介绍了缪子反常磁矩的实验与理论现状,特别是北京谱仪实验上相关的研究成果,并展望了未来缪子反常磁矩的实验测量与理论计算。     

反常磁矩对弱磁场弱相互作用费米气体热力学性质的影响

考虑费米子的反常磁矩, 运用赝势法和热力学理论, 导出弱磁场中弱相互作用费米气体自由能的解析式, 以此为基础给出高温和低温情况下系统热力学性质, 分析反常磁矩对热力学性质的影响机理. 研究表明: 反常磁矩对热力学性质的影响与温度相关, 而且这种影响随温度的上升在低温区是增大的, 在高温区是减小的; 对于系统的化学势、内能, 反常磁矩加强了磁场的影响, 弱化了相互作用的影响; 对于系统的热容量, 反常磁矩在低温区使其减小, 在高温区使其增加.