Magnetophonon resonance in double quantum wells

Abstract

The experimental results obtained for the magnetotransport in pulsed magnetic fields in the InGaAs/InAlAs double quantum well ͑DQW͒ structures of two different shapes of wells and different values of the electron density are reported. The magnetophonon resonance ͑MPR͒ was observed for both types of structures within the temperature range 77-125 K. Four kinds of LO phonons are taken into account to interpret the MPR oscillations in the DQW and a method of the Landau level calculation in the DQW is elaborated for this aim. The peculiarity of the MPR in the DQW is the large number of the Landau levels caused by SAS splitting of the electron states ͑splitting on the symmetric and anti-symmetric states͒ and the large number of the phonon assistance electron transitions between Landau levels. The significant role of the carrier statistics is shown too. The behavior of the electron states in the DQWs at comparably high temperatures has been studied using the MPR. It is shown that the Huang and Manasreh ͓Manasreh ͓Phys. Rev. B 54, 2044 ͑1996͔͒ model involving screening of exchange interaction is confirmed.

Optical detection of symmetric and antisymmetric states in double quantum wells at room temperature

“…The general scheme of the LL energies calculations in DQWs was elaborated in our previous work 15 where the screening of the exchange interaction in DQWs was taken into account according to Ref. 21.…”

“…The last transitions could mix the symmetric and antisymmetric states but they are essential at high magnetic fields ͑above 10 T͒. 15 Thus, we could expect that if the magnetophonon resonance condition is not fulfilled, the symmetric and antisymmetric states in the DQWs are not mixed and the whole electron system consists of two subsystems characterized by two different quasi-Fermi levels.…”

High mobility In0.75Ga0.25As quantum wells in an InAs phonon lattice

“…This is different from what is reported in Ref. [8] that AlAs-like phonon (B f = 19.2 T) is seen at around 9 T. The fact that the InAs-like phonon is dominant in these samples is unlikely to be due to the contribution of InAs-like phonons in the InAlAs barrier as stated in the work based on InGaAs/InAlAs heterojunctions [7] since the QW width in this work is 30 nm, which is much wider than the previously studied system [6,9]. There are three possible reasons why phonons from the barriers can play an important role in MPR: 1).…”

Landau levels and shallow donor states in GaAs/AlGaAs multiple quantum wells at megagauss magnetic fields

“…This problem specifically concerns the MQWs based on the GaAs/AlGaAs heterostructures where the donor centers can exist both in the wells and barriers. In addition to the useful applications of MQWs to infrared photodetectors [14][15][16][17] , light-emitting diode array (emitters) [18][19][20][21] and cascade lasers [22][23][24][25] , nonlinear optics 26 , phononic crystals 27 they provide a test system for the study of electron correlation in two dimensional electron gas (2DEG) when the electrons are spatially conned by the potentials of closely spaced multilayers [28][29][30][31][32][33][34][35] .…”