Magnetoplasma excitations of two-dimensional anisotropic heavy fermions in AlAs quantum wells

Abstract

The spectra of plasma and magnetoplasma excitations in a two-dimensional system of anisotropic heavy fermions were investigated for the first time. The spectrum of microwave absorption by disklike samples of stressed AlAs quantum wells at low electron densities showed two plasma resonances separated by a frequency gap. These two plasma resonances correspond to electron mass principle values of (1.10 ± 0.05)m0 and (0.20 ± 0.01)m0. The observed results correspond to the case of a single valley strongly anisotropic Fermi surface. It was established that electron density increase results in population of the second valley, manifesting itself as a drastic modification of the plasma spectrum. We directly determined the electron densities in each valley and the inter-valley splitting energy from the ratio of the two plasma frequencies.

Fine structure of cyclotron resonance in a two-dimensional electron system

“…The first observation of CR in 2DESs was reported for charged carriers in an inversion layer on Si [4, 5]. Subsequently, CR spectroscopy has been successfully applied to research on many two-dimensional systems, for example, isotropic 2D carriers in GaAs heterostructures [6][7][8], composite fermions [9], heavy fermions in MgZnO/ZnO heterojunctions [10,11], and anisotropic heavy fermions in AlAs quantum wells [12,13].It is widely believed that the cyclotron resonance originates from the dimensional magnetoplasma resonance [15,16,20]. The frequency of the hybrid cyclotron magnetoplasma mode is described by the equation…”

“…The first observation of CR in 2DESs was reported for charged carriers in an inversion layer on Si [4, 5]. Subsequently, CR spectroscopy has been successfully applied to research on many two-dimensional systems, for example, isotropic 2D carriers in GaAs heterostructures [6][7][8], composite fermions [9], heavy fermions in MgZnO/ZnO heterojunctions [10,11], and anisotropic heavy fermions in AlAs quantum wells [12,13].…”

Plasmons and magnetoplasmons in partially bounded two-layer electron systems

“…where V p is the velocity of gated plasmons and κ is the dielectric permittivity in the space between 2DES and the gate. Initially observed in 2D systems of electrons on a liquid helium surface 3 as well as in silicon inversion layers [4][5][6] , 2D plasmons continue to be actively investigated in various 2D structures [7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] . It should also be mentioned that 2D plasmons, especially in structures with metal gates, have proven promising as detectors and emitters of radiation in the terahertz range [22][23][24][25][26][27][28][29][30][31] .…”

Piezoplasmonics: Strain-induced tunability of plasmon resonance in AlAs quantum wells

“…The collective plasma excitations in the 2DES with anisotropic energy spectrum possess a number of unique properties. In particular, the discovery of a gap in the spectrum of plasma excitations in perfectly symmetric circular samples [16][17][18]. It was shown that inter-valley energy splitting significantly influences the plasmon spectrum through redistribution of charge carriers between X x and X y valleys.…”

“…The magnetodispersion curve for unstrained sample (see Fig. 1(c), blue dots) was studied in our previous work [16], where the following zero-field frequencies were extracted: Ω [100] /2π = (8.9 ± 0.2) GHz and Ω [010] /2π = (15.7 ± 0.2) GHz, and ∆E = (0.90 ± 0.05) meV. In the present paper we apply the same procedure for a strained sample (red dots in Fig.…”