Quantum corrections to the conductivity in systems with strong spin-orbit splitting of the spectrum

Quantum corrections to the conductivity in a 2D system with a smooth random potential and strong spin-orbit splitting of the spectrum are studied. It is shown that the interference correction is positive and, right down to very low temperatures, does not exceed in magnitude the negative correction due to the electron-electron interaction. Pis’ma Zh. éksp. Teor. Fiz. 68, No. 4, 314–319 (25 August 1998)     

Observation of spin-orbit splitting in lambda single-particle states

The spin-orbit splitting of Lambda single-particle states in (13)(Lambda)C was measured. The 13C(K-,pi(-))(13)(Lambda)C reaction was used to excite both the 1/2(-) and 3/2(-) states simultaneously, which have predominantly 12C(0(+)) x p(Lambda) configuration. gamma rays from the states to the ground state were measured in coincidence with the pi(-)'s, by which ls splitting was found to be 152+/-54(stat)+/-36(syst) keV. The value is 20-30 times smaller than exhibited by the ls splitting in the nuclear shell model. This value gives us new insight into the YN interaction.     

Magnetoplasma oscillations in a 2D electron system with spin-orbit interaction

The magnetoplasmon spectrum in a 2D electron plasma is investigated theoretically taking into account the spin—orbit interaction in the Rashba model. The expression is derived for the polarization operator in the semiclassical range of magnetic fields (in which the Fermi energy eF is much larger than the Landau quantum). Approximate analytic formulas are obtained for spin—plasmon branches. The dependences of plasma wave frequencies on the wavevector and magnetic field are calculated from a numerical solution of the dispersion equation. In addition, the magnetic field and frequency dependences of the plasmon absorption intensity are constructed. The absorption intensity at the peak is found to be sensitive to the spin—orbit interaction constant.     

Changes in the spectrum of surface states of Si−SiO2 structures stimulated by a weak magnetic field

Weak-signal methods are used to study long-term changes in the spectrum of surface states (STs) of n-Si−SiO₂ systems after exposure to a steady magnetic field of 10⁵ A/m. The spectrum changes appreciably within the first 3–5 days after magnetic treatment. The initial spectrum is then slowly partially reestablished. The following defects play an important role in the restructuring of the ST spectrum: singly negatively charged double vacancy: vacancy+phosphorus. In the event of long-term changes in ST density the lifetime of the minority carriers in the space-charge region has three stages differing in the character of the changes in the properties of the magnetically treated structures. It is established that the latter changes depend on intrinsic defects in the semiconductor. It is also found that complex changes take place in the recombination properties of Si−SiO₂ structures after magnetic treatment. Tomsk University of Control Systems and Electronics. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 8, pp. 93–98, August, 1997.     

Effective conductivity of 2D isotropic two-phase systems in a magnetic field

Using the linear fractional transformation, which connects the effective conductivities \(\hat \sigma _e \) of isotropic two-phase systems with and without magnetic field, explicit approximate expressions for \(\hat \sigma _e \) in a magnetic field are obtained. They allow one to describe \(\hat \sigma _e \) of various inhomogeneous media at arbitrary phase concentrations x and magnetic fields. The x-dependence plots of \(\hat \sigma _e \) at some values of inhomogeneity and magnetic field are constructed. Their behavior is qualitatively compatible with the existing experimental data. The obtained results are applicable to different two-phase systems (regular and irregular as well as random), which satisfy the symmetry and self-duality conditions, and admit direct experimental checking.     

Effects of magnetic field and spin-orbit interaction on energy levels in 1D quantum wire: analytical solution

In this paper, we study the effects of a perpendicular magnetic field and spin-orbit interaction (SOI) on energy levels of a quasi-one-dimensional quantum wire. Here, we solve analytically the Schr?dinger equation to obtain energy levels and wave functions. The results show that the splitting at k?=?0 is not constant and it depends on the subband. This variable splitting is due to a symmetry breaking effect when magnetic field and SOI are simultaneously present.     

Light scattering by a 2D electron system with spin-orbit interaction in a strong magnetic field

We theoretically investigate light scattering by electrons of a 2D system in a strong magnetic field perpendicular to the plane of the system (the filling factor is smaller than two, i.e., only the states of the zeroth Landau level are filled). Analysis is carried out in the resonance approximation, in which the frequencies of the incident and scattered light are close to the effective separation between the conduction band and one of the branches of the valence band of the semiconductor. Spin splitting of the Landau level in the conduction band associated with Zeeman and the spin-orbit interactions is taken into account. The dynamic screening effects are considered in the random phase approximation (RPA).     

Lateral-surface superlattices in systems with spin-orbit coupling: Quantum states and bloch oscillations in an electric field

The quantum states of a two-dimensional electron gas with spin-orbit coupling located in the periodic potential of a lateral-surface superlattice are studied. The spin-split energy bands and the distribution of spin projections in the Brillouin zone are constructed. Bloch oscillations accompanied by spin precession in superlattices with spin-orbit coupling located in a constant electric field are studied.     

Electric and magnetic field modulated energy dispersion,conductivity and optical response in double quantum wire with spin-orbit interactions

We study the influence of electric field on the electronic energy band structure, zero-temperature ballistic conductivity and optical properties of double quantum wire. System described by double-well anharmonic confinement potential is exposed to a perpendicular magnetic field and Rashba and Dresselhaus spin-orbit interactions. Numerical results show up that the combined effects of internal and external agents cause the formation of crossing, anticrossing, camel-back/anomaly structures and the lateral, downward/upward shifts in the energy dispersion. The anomalies in the energy subbands give rise to the oscillation patterns in the ballistic conductance, and the energy shifts bring about the shift in the peak positions of optical absorption coefficients and refractive index changes.     

Tunneling transverse to a magnetic field and its occurrence in correlated 2D electron systems

We investigate tunneling decay in a magnetic field. Because of broken time-reversal symmetry, the standard WKB technique does not apply. The decay rate and the outcoming wave packet are found from the analysis of the set of the particle Hamiltonian trajectories and its singularities in complex space. The results are applied to tunneling from a strongly correlated 2D electron system in a magnetic field parallel to the layer. We show in a simple model that electron correlations strongly affect the tunneling rate.     

Quantum high-frequency conductivity oscillations in graphene multilayers and nodal semimetals in a tilted magnetic field

A new type of angular oscillations of the high-frequency conductivity for conductors with a band-contact line has been predicted. The effect is caused by groups of charge carriers near the self-intersection points of the Fermi surface, where the electron energy spectrum is near-linear and can be described by anisotropic Dirac cone model. The amplitude of the resonance peaks satisfies the simple sum rule. The ease in changing the degree of anisotropy of the Dirac cone due to the angle of inclination of the magnetic field makes the considered type of oscillations attractive for experimental observation of relativistic effects.     

Commensurability oscillations in fast particle energy loss to a density modulated 2DEG in a magnetic field

We examine fast particle energy loss as a probe of the properties of a density modulated 2DEG in a normal magnetic field. In the high velocity limit, the local plasmon spectrum makes two separate contributions to energy loss for both the cases in which the particle velocity is parallel and perpendicular to the planar 2DEG. The inter-Landau band plasmon makes a distinct contribution to energy loss through excitation of the hybrid 2D magnetoplasmon. The other local plasmon, associated with the spread of a Landau level into a miniband by application of the periodic potential associated with the density modulation contributes to energy loss with features corresponding to Shubnikov-de Haas oscillations jointly with an amplitude envelope exhibiting oscillations associated with the commensurability of the modulation period and the cyclotron radius at the Fermi energy.     

Tunneling and energy splitting in an asymmetric double-well potential

An asymmetric double-well potential is considered, assuming that the minima of the wells are quadratic with a frequency ω and the difference of the minima is close to a multiple of ?ω. A WKB wave function is constructed on both sides of the local maximum between the wells, by matching the WKB function to the exact wave functions near the classical turning points. The continuities of the wave function and its first derivative at the local maximum then give the energy-level splitting formula, which not only reproduces the instanton result for a symmetric potential, but also elucidates the appearance of resonances of tunneling in the asymmetric potential.     

The magnetic field of Langmuir oscillations

The small-scale quasistationary magnetic field appearing in a plasma exhibiting plasma oscillations is considered. It is shown that this magnetic field is capable of leading to dissipation of the electromagnetic waves propagating in the plasma. Zh. Tekh. Fiz. 67, 140–141 (June 1997)     

Wave packet splitting and zitterbewegung in two-dimensional semiconductor structures with spin-orbit coupling

Dynamics of electron wave packets in an asymmetric quantum well in the presence of Rashba spinorbit coupling was analytically and numerically studied. Electron Green’s functions were introduced and the evolution of 1D and 2D wave packets was studied. The effect of packet splitting caused by the presence of two branches with different chiralities in the Rashba Hamiltonian spectrum and zitterbewegung, i.e., packet center’s jitter, was studied. Spatial components of the spin density were calculated. It was shown that the component of the spin density S _y in split parts of the wave packet has opposite signs, and two other spin density components oscillate in space between scattering packets.