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Dae Kwan Kim

Publications and source records attributed to Dae Kwan Kim.

6 recordsLinked to original sources
arXiv2001

Impact of optical phonon scattering on magnetotransport in double-barrier heterostructures

The transport in double-barrier heterostructures of electrons interacting with longitudinal optical phonons in the presence of parallel electric and magnetic fields is analyzed theoretically with the aid of a 3-dimensional quantum transport simulator. Inter Landau state transitions induced by LO-phonon scattering-assisted resonant-tunneling is shown to be an important process with a probability comparable to that of intra Landau state scattering. Analysis of the current-voltage characteristics reveals also that the current peak is a periodic function of the inverse of the magnetic field, with a period dependent on the quasi-resonant energy level.

cond-mat.mes-hall↗
arXiv2001

Onset voltage shift due to non-zero Landau ground state level in coherent magnetotransport

Coherent electron transport in double-barrier heterostructures with parallel electric and magnetic fields is analyzed theoretically and with the aid of a quantum simulator accounting for 3-dimensional transport effects. The onset-voltage shift induced by the magnetic field in resonant tunneling diodes, which was previously attributed to the cyclotron frequency $w_c$ inside the well is found to arise from an upward shift of the non-zero ground (lowest) Landau state energy in the entire quantum region where coherent transport takes place. The spatial dependence of the cyclotron frequency is accounted for and verified to have a negligible impact on resonant tunneling for the device and magnetic field strength considered. A correction term for the onset-voltage shift arising from the magnetic field dependence of the chemical potential is also derived. The Landau ground state with its nonvanishing finite harmonic oscillator energy $ \hbar w_c /2$ is verified however to be the principal contributor to the onset voltage shift at low temperatures.

cond-mat.mes-hall↗
arXiv1998

Fluctuation correction to the ground state energy density of a dilute Bose gas in the functional Schrödinger picture

A dilute Bose gas system is studied using the functional Schrödinger picture theory. The ground state properties are obtained by solving the infinite dimensional Schrödinger equation variationally. It is shown that a shifted Gaussian trial wavefunctional enables us to calculate a higher order correction, which corresponds to the fluctuation contribution from the condensate. The obtained term is compared with the quantum correction arising from the low energy $3 \to 3$ scattering.

cond-mat.stat-mech↗
arXiv1997

Finite Density Effect in the Gross-Neveu Model in a Weakly Curved $R^1\times S^2$ Spacetime

The three-dimensional Gross-Neveu model in $R^{1} \times S^{2}$ spacetime is considered at finite particles number density. We evaluate an effective potential of the composite scalar field $σ(x)$, which is expressed in terms of a scalar curvature $R$ and nonzero chemical potential $μ$. We then derive the critical values of $(R,μ)$ at which the system undergoes the first order phase transition from the phase with broken chiral invariance to the symmetric phase.

hep-th↗
arXiv1997

The O(N) Nonlinear Sigma Model in the Functional Schrödinger Picture

We present a functional Schrödinger picture formalism of the (1+1)-dimensional $O(N) $ nonlinear sigma model. The energy density has been calculated to two-loop order using the wave functional of a gaussian form, and from which the nonperturbative mass gap of the boson fields has been obtained. The functional Schrödinger picture approach combined with the variational technique is shownto describe the characteristics of the ground state of the nonlinear sigma model in a transparent way.

hep-th↗