INVESTIGADORES
TAMBORENEA Pablo Ignacio
artículos
Título:
Spin instabilities in coupled semiconductor quantum wells
Autor/es:
R. J. RADTKE; P. I. TAMBORENEA; S. DAS SARMA
Revista:
PHYSICAL REVIEW B - CONDENSED MATTER AND MATERIALS PHYSICS
Editorial:
American Physical Society
Referencias:
Año: 1996 vol. 54 p. 13832 - 13858
ISSN:
0163-1829
Resumen:
We study the magnetic phases of two coupled two-dimensional electron
gases in order to determine under what circumstances these phases may
occur in real semiconductor quantum wells, and what the experimental
properties of the broken-symmetry ground states may be. Within the
local-density approximation to time-dependent density-functional theory
(DFT), we find a phase transition signaled by the vanishing of the
intersubband spin-density excitations at low but accessible (∼1010?1011 cm−2)
electron densities. Through a self-consistent Hartree-Fock calculation,
we associate this transition with an antiferromagnetic phase and study
the phase diagram, thermodynamics, and collective modes in it. The
collective modes are in principle observable in inelastic
light-scattering experiments, and we discuss the implications of our
calculations for these measurements. We also examine the ferromagnetic
transition in both single and double quantum wells within the
local-spin-density approximation to DFT, and obtain a critical density
which depends on the well width and which is far below that of the
antiferromagnetic transition.