Plasmon properties in dilute, two-dimensional electron liquids
Sprache des Vortragstitels:
Strongly Coupled Coulomb Systems
Sprache des Tagungstitel:
Two-dimensional (2D) electron systems, where presently Dirac liquids and insulating oxide surfaces deserve much attention, have remained a topic of significant importance also in semiconductor heterostructures. Compared to bulk systems, the 2D realizations show much more pronounced correlations, key examples being the collective modes such as plasmons and magnons. For highly dilute semiconductor quantum wells it is mandatory to account for dynamic multi-particle fluctuations, in particular two-particles-two-holes (2p2h) excitations. This dynamic pair theory yields a substantially lower plasmon energy than static theories, and, consequently, a much smaller critical wave vector for Landau damping. The plasmon broadening by pair excitations turns out to be rather small. The next step is the
extension to spin-sensitive effective interactions to study the spin-spin and the spin-density linear response functions. These promise new insights via the longitudinal spin plasmon and a highly interesting 'magnetic antiresonance'. We discuss unfamiliar excitation regimes in
the partially spin-polarized electron liquid where one (the spin-density response) or both (spin-spin response and spin-density response) vanish.