arXiv subjects

D. C. Marinescu

Publications and source records attributed to D. C. Marinescu.

27 records · Page 2Linked to original sources

arXiv2007

Finite-size Effects in a Two-Dimensional Electron Gas with Rashba Spin-Orbit Interaction

Within the Kubo formalism, we estimate the spin-Hall conductivity in a two-dimensional electron gas with Rashba spin-orbit interaction and study its variation as a function of disorder strength and system size. The numerical algorithm employed in the calculation is based on the direct numerical integration of the time-dependent Schrodinger equation in a spin-dependent variant of the particle source method. We find that the spin-precession length, L_s controlled by the strength of the Rashba coupling, establishes the critical lengthscale that marks the significant reduction of the spin-Hall conductivity in bulk systems. In contrast, the electron mean free path, inversely proportional to the strength of disorder, appears to have only a minor effect.

cond-mat.mes-hall↗

arXiv2006

Electron-Dephasing Time in A Two-Dimensional Spin-Polarized System with Rashba Spin-Orbit Interaction

We calculate the dephasing time $τ_ϕ(B)$ of an electron in a two-dimensional quantum well with a Rashba spin-orbit interaction, spin-polarized by an arbitrarily large magnetic field parallel to the layer. $τ_ϕ(B)$ is estimated from the logarithmic corrections to the conductivity, within a perturbative approach, that assumes weak isotropic disorder scattering. Our result indicates that for any value of the magnetic field, the dephasing rate changes with respect to its unpolarized state value by a universal function whose parameter is the ratio of the Zeeman splitting energy $(E_Z)$ to the spin-orbit interaction $(E_{SOI})$, confirming the experimental report published in Phys. Rev. Lett. {\bf 94}, 186805 (2005) . In the high field limit, when $E_Z>>E_{SOI}$, the dephasing rate saturates and reaches asymptotically to a value equal to twice the spin relaxation rate.

cond-mat.mes-hall↗

arXiv2005

Longitudinal and spin-Hall conductance of a two-dimensional Rashba system with arbitrary disorder

We calculate the longitudinal and spin-Hall conductances in four-lead bridges with Rashba - Dresselhaus spin-orbit interactions. Numerical results are obtained both within Landauer-Buttiker formalism and by the direct evaluation of the Kubo formula. The microscopic Hamiltonian is obtained in the tight-binding approximation in terms of the neareast-neighbor hopping integral $t$, the Rashba spin-orbit coupling $V_R$, the Dresselhaus spin-orbit coupling $V_D$ and an Anderson-like, on-site disorder energy strength $W$. We reconfirm that below a critical disorder threshold, the spin-Hall effect is present. Further, we study the effect on the two conductivities of the Fermi energy, Rashba/Dresselhaus coefficient ratio, and system size.

cond-mat.mes-hall↗

arXiv2004

The Spin Mass of an Electron Liquid

We show that in order to calculate correctly the {\it spin current} carried by a quasiparticle in an electron liquid one must use an effective "spin mass" $m_s$, that is larger than both the band mass, $m_b$, which determines the charge current, and the quasiparticle effective mass $m^*$, which determines the heat capacity. We present microscopic calculations of $m_s$ in a paramagnetic electron liquid in three and two dimensions, showing that the mass enhancement $m_s/m_b$ can be a very significant effect.

cond-mat.str-el↗

arXiv2003

Hartree-Fock energy of a density wave in a spin polarized two-dimensional electron gas

We calculate the Hartree-Fock energy of a density-wave in a spin polarized two-dimensional electron gas using a short-range repulsive interaction. We find that the stable ground state for a short-range potential is always either the paramagnetic state or the uniform ferromagnetic state. The energy of a density-wave state is, however, reduced by a factor proportional to (1 - zeta^2), where zeta is the polarization of the electron gas. Since this situation occurs in the most unfavorable conditions (short-range repulsive interaction) it is therefore conceivable that by including higher order many-body corrections to the interaction a density-wave ground state is indeed found to be stable.

cond-mat.str-el↗

arXiv2003

Pair distribution function in a two-dimensional electron gas

We calculate the pair distribution function, $g(r)$, in a two-dimensional electron gas and derive a simple analytical expression for its value at the origin as a function of $r_s$. Our approach is based on solving the Schrödinger equation for the two-electron wave function in an appropriate effective potential, leading to results that are in good agreement with Quantum Monte Carlo data and with the most recent numerical calculations of $g(0)$. [C. Bulutay and B. Tanatar, Phys. Rev. B {\bf 65}, 195116 (2002)] We also show that the spin-up spin-down correlation function at the origin, $g_{\uparrow \downarrow}(0)$, is mainly independent of the degree of spin polarization of the electronic system.

cond-mat.str-el↗

arXiv2002

Local field factors in a polarized two-dimensional electron gas

We derive approximate expressions for the static local field factors of a spin polarized two-dimensional electron gas which smoothly interpolate between their small- and large-wavevector asymptotic limits. For the unpolarized electron gas, the proposed analytical expressions reproduce recent diffusion Monte Carlo data. We find that the degree of spin polarization produces important modifications to the local factors of the minority spins, while the local field functions of the majority spins are less affected.

cond-mat.str-el↗

arXiv2002

Effective electron-electron interaction in a two dimensional paramagnetic system

We analyze the effective electron-electron interaction in a two dimensional polarized paramagnetic system. The spin degree of freedom, s, is manifestly present in the expressions of spin dependent local field factors that describe the short range exchange (x) and correlation (c) effects. Starting from the exact asymptotic values of the local field correction functions for large and small momentum at zero frequency we obtain self-consistent expressions across the whole spectrum of momenta. Then, the effective interaction between two electrons with spins s and s' is calculated. We find that the four effective interactions, up-up, up-down, down-up and down-down, are different. We also obtain their qualitative dependence on the electronic density and polarization and note that these results are independent of the approximation used for the local field correction functions at intermediate momenta.

cond-mat.str-el↗

arXiv1997

Quantum Hall Spherical Systems: the Filling Fraction

Within the newly formulated composite fermion hierarchy the filling fraction of a spherical quantum Hall system is obtained when it can be expressed as an odd or even denominator fraction. A plot of $ν\frac{2S}{N-1}$ as a function of $2S$ for a constant number of particles (up to N=10001) exhibits structure of the fractional quantum Hall effect. It is confirmed that $ν_e +ν_h=1$ for all particle-hole conjugate systems, except systems with $N_e =N_h$, and $N_e=N_h \pm 1$.

cond-mat.mes-hall↗