Uniform Perpendicular Magnetic Field Research Articles

Semiclassical theory of magnetization for a two-dimensional non-interacting electron gas

We compute the semiclassical magnetization and susceptibility of non-interacting electrons, confined by a smooth two-dimensional potential and subjected to a uniform perpendicular magnetic field, in the general case when their classical motion is chaotic. It is demonstrated that the magnetization per particle m(B) is directly related to the staircase function N(E), which counts the single-particle levels up to energy E. Using Gutzwiller's trace formula for N, we derive a semiclassical expression for m. Our results show that the magnetization has a non-zero average, which arises from quantum corrections to the leading-order Weyl approximation to the mean staircase and which is independent of whether the classical motion is chaotic or not. Fluctuations about the average are due to classical periodic orbits and do represent a signature of chaos. This behaviour is confirmed by numerical computations for a specific system.

Correlations and Local Field Corrections for a Two-Dimensional Electronic System in an External Magnetic Field

It is shown that the correlation effects on a two-dimensional electron gas in a uniform perpendicular magnetic field are significantly affected by a strong magnetic field. A dielectric function approach is used to go beyond the RPA by improving the effective potential. This is done by including the local field correction Gq to the mean Hartree field. Following Singwi et al. we replace the two-particle distribution function ƒ2(r, p; r′, p′; t) by a product of two equilibrium one-particle distribution functions ƒ(r, p; t)ƒ(r′, p′; t) g(r − r′), where g(r) is the static equilibrium pair correlation function. We have shown that the form of the effective potential is not altered by a uniform magnetic field. Both Gq and the pair correlation function oscillate as functions of the magnetic field. The local field correction has maxima at half-odd integer fillings and minima at integer filling factors. As a result, the effective inter-particle potential has enhanced oscillations. The effect due to correlations on the plasma excitations is also discussed.

Quantum magnetotransport in lateral surface superlattices

We calculate the diffusion constant of a two-dimensional electron gas (2DEG) in a uniform perpendicular external magnetic field using the short-time expansion of the Kubo–Greenwood formula. We model the 2DEG as a one-component plasma. The two-body and three-body correlation functions are obtained from the hypernetted-chain integral equation theory and the Kirkwood superposition approximation, respectively. We compare the diffusion constant at two different temperatures. At the lower temperature, the diffusion constant increases as the magnetic field is increased but decreases with increasing magnetic field at the higher temperature. We compare our results when only two-body correlations are taken into account with those when both two-body and three-body correlations are included. These results may be interpreted as being due to the competition between the magnetic force and the force exerted on the target particle by the surrounding electrons in the 2DEG in the presence of a perpendicular magnetic field.

Weak-coupling expansion for the free energy of the magneto-polaron in two dimensions

Previous weak-coupling expansions of the ground-state energy for a Frohlich type polaron in two dimensions subject to a perpendicular uniform magnetic field are extended to non-zero temperatures by using the path-integral representation. For every temperature the second-order contribution becomes positive for sufficiently high fields implying that a seemingly natural generalisation of the Jensen-Feynman inequality does not exist.

On the Landau-level broadening by deltaor constantly correlated random potentials

For the averaged density of states of non-interacting electrons in an infinite plane subject to a perpendicular uniform magnetic field and a delta-correlated random potential a scaling relation is obtained by using Feynman path integrals. As an example we rederive the density of states of the Landau-Lloyd model, give a closed-form expression and show that the absence of level mixing is a general property of the Cauchy-Lorentzian randomness. The latter is also true for constantly correlated randomness with an arbitrary single-site distribution.

Nonlinear upper hybnd drift waves for /spl rlhar2/E ⊥/spl rlhar2/B0 in the vlasov-maxwell approximation

Upper hybrid drift waves are found as a special solution to a Vlasov-Maxwell plasma which has a longitudinal electric field and a perpendicular uniform magnetic field. A single-species plasma with a constant-density mobile neutralizing background supports spatially varying disturbances that oscillate at the upper hybrid frequency. The general functional dependences of the electric field, the plasma number density, and the one-particle distribution function for the special case are found from more general Vlasov-Maxwell equations invariant under a Lie group point transformation. The one-particle distribution function for the plasma is a function of the Liouville invariant, which is the energy in the generalized Bernstein-Greene-Kruskal (BGK) reference frame, and the momentum in the drift direction.

Nonplanar textures ofHe3−Ain a slab

The Ginzburg-Landau theory is used to study the texture of superfluid /sup 3/He-A in a slab subject to a uniform perpendicular magnetic field and a weak oscillatory hydrodynamic flow. For steady or low-frequency motion, l undergoes synchronous rotation about H; at high frequency, the orbital viscosity suppresses such motion, producing a planar texture. The integrated mass current provides an operational definition of the mean superfluid density; improved calculations agree somewhat better with available experimental data.

Textures in superfluidHe3−A: Large deformations in a slab

The Ginzburg-Landau equations are used to study deformed configurations of $^{3}\mathrm{He}\ensuremath{-}A$ in a slab subject to a uniform perpendicular magnetic field. The resulting textures determine the mean superfluid density and longitudinal and transverse NMR absorption spectra near ${T}_{c}$ for various widths and applied fields.

Coherent states of a charged particle in a time-dependent uniform electromagnetic field of a plane current

All invariants, the coherent states and the Green function are constructed for a particle moving in time-dependent uniform perpendicular electric and magnetic fields. The transition amplitudes and probabilities between the “energy” levels and their generating functions are constructed too. The limit cases of the problem under consideration are considered.