Negative differential resistance in a finite-thickness quasi-two-dimensional electron gas mediated by spin-orbit interactions

E. Nakhmedov, O. Alekperov, and R. Oppermann

Phys. Rev. B 83, 153416 – Published 22 April 2011

Abstract

The effects of spin-orbit interactions on the energy spectrum, Fermi surface, and spin dynamics in structural- and bulk-inversion asymmetric quasi-two-dimensional structures with a finite thickness are studied in the presence of a parabolic transverse confining potential. A one-particle quantum mechanical problem in the presence of an in-plane magnetic field is solved in a numerically exact way. The interplay of spin-orbit interactions with the orbital and Zeeman effects of an in-plane magnetic field yields a multivalley subband structure that is typical for the realization of the Gunn effect. A possible Gunn-effect-mediated spin accumulation is discussed.

Received 14 February 2011

DOI:https://doi.org/10.1103/PhysRevB.83.153416

Authors & Affiliations

E. Nakhmedov^1,2, O. Alekperov², and R. Oppermann¹

¹Institut für Theoretische Physik, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
²Institute of Physics, Azerbaijan National Academy of Sciences, H. Cavid str. 33, AZ1143 Baku, Azerbaijan

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Vol. 83, Iss. 15 — 15 April 2011

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Figure 1
Dependence of the energy spectrum on Rashba and Dresselhaus SO coupling constants, as well as on the orbital and spin effects of the in-plane magnetic field. (a) $E$ vs $k_{y}$ is shown in the absence of the magnetic field at ${k̃}_{x} = 0$ , ${f̃}_{g} = 0.3$ , $α̃ = 0.5$ , and $β̃ = 0$ by dashed (green) curves; ${k̃}_{x} = 0.4$ , ${f̃}_{g} = 0$ , and $α̃ = β̃ = 0.6$ by dot-dashed (blue) curves; and ${k̃}_{x} = 0.4$ , ${f̃}_{g} = 0$ , $α̃ = 0.8$ , and $β̃ = 0.4$ by solid (red) curves. (b) The energy spectrum is also shown under the in-plane magnetic field ${ω̃}_{B} = 0.7$ , $g̃ = 0.2$ , ${k̃}_{x} = 0.2$ , and $β̃ = 0.4$ , but for different values of $α̃$ and ${f̃}_{g}$ : $α̃ = 0.4$ , ${f̃}_{g} = 0$ by dashed (green) curves; $α̃ = 1.2$ , ${f̃}_{g} = 0.3$ by dot-dashed (blue) curves; and $α̃ = 0.9$ , ${f̃}_{g} = 0$ by solid (red) curves.Reuse & Permissions
Figure 2
Dependence of the energy spectrum on the in-plane magnetic field (a) in the absence ( $g̃ = 0$ ) and (b) in the presence ( $g̃ = 0.2$ ) of Zeeman splitting at ${f̃}_{g} = 0$ . The parameters ${k̃}_{x} = 0.4$ , ${k̃}_{y} = 0.5$ , $α̃ = 0.6$ , and $β̃ = 0.4$ correspond to the dotted (green) curve. The dot-dashed (blue) and solid (red) curves depict the cases ${k̃}_{x} = 0.2$ , ${k̃}_{y} = 1.4$ , $α̃ = 0.8$ , $β̃ = 0.4$ and ${k̃}_{x} = 0.4$ , ${k̃}_{y} = 1.8$ , $α̃ = 0.6$ , $β̃ = 0.4$ , respectively.Reuse & Permissions
Figure 3
Fermi surface of electrons in the first transverse-quantized level. (a) In the absence of a magnetic field ( ${ω̃}_{B} = g̃ = 0$ ), the dot-dashed (green) curves correspond to $α̃ = 0.5$ , $β̃ = 0$ , ${f̃}_{g} = 0.3$ ; dashed (blue) curves to $α̃ = 0.5$ , $β̃ = 0.4$ , ${f̃}_{g} = 0$ ; and solid (red) curves to $α̃ = β̃ = 0.5$ , ${f̃}_{g} = 0$ . (b) Dot-dashed (green) curves correspond to ${ω̃}_{B} = g̃ = 0$ , ${f̃}_{g} = 0.3$ for $α̃ = β̃ = 0.5$ ; dashed (blue) curves to ${ω̃}_{B} = 0.7$ , $g̃ = 0$ , ${f̃}_{g} = 0$ for $α̃ = β̃ = 0.5$ ; and solid (red) curves to ${ω̃}_{B} = 0.7$ , $g̃ = 0.3$ , ${f̃}_{g} = 0$ for $α̃ = 0.5$ , $β̃ = 0.4$ .Reuse & Permissions
Figure 4
(a) Two-valley spectrum corresponding to the lower branch of the first and second transverse-quantized levels, with $α̃ = 0.9$ , $β̃ = 0.4$ , ${ω̃}_{B} = 0.7$ , $g̃ = 0.2$ , ${f̃}_{g} = 0$ , and ${k̃}_{x} = 0.2$ shown by solid (red) curves, and $α̃ = 1.2$ , $β̃ = 0.4$ , ${ω̃}_{B} = 0.8$ , $g̃ = 0.3$ , ${f̃}_{g} = 0.3$ , and ${k̃}_{x} = 0.4$ shown by the dot-dashed (dark blue) curve. (b and d) Dependence of (b) the average drift velocity $v$ and (d) the spin accumulation $P$ on the electric field $E$ for $μ_{1} = 10$ $m^{2}$ /(V s) and $T = 4.2$ K, $μ = μ_{2} / μ_{1} = 0.02$ , and $R = 50$ . (c) $P$ vs $E$ for $μ_{1} = 20$ $m^{2}$ /(V s) and $T = 50$ K, $μ = μ_{2} / μ_{1} = 0.1$ , and $R = 10$ . The four values of the activation energy $Δ E = 4$ , 6, 8, and 10 meV correspond to dotted (green), dashed (light blue), dot-dashed (dark blue), and solid (red) curves in each figures.Reuse & Permissions

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