Theoretical analysis of radiation-induced magnetoresistance oscillations in high-mobility two-dimensional electron systems

Abstract

We present a detailed theoretical investigation of the radiation induced giant magnetoresistance oscillations recently discovered in high-mobility twodimensional electron gas. Electron interactions with impurities, and transverse and longitudinal acoustic phonons in GaAs-based heterosystems are considered simultaneously. Multiphoton-assisted impurity scatterings are shown to be the primary origin of the resistance oscillation. Based on the balance-equation theory developed for magnetotransport in Faraday geometry, we are able not only to reproduce the observed period, phase and the negative resistivity of the main oscillations, but also to predict the secondary peak/valley structures relating to two-photon and three-photon processes. The dependence of the magnetoresistance oscillation on microwave intensity, the role of dc bias current and the effect of elevated electron temperature are discussed. Furthermore, we propose that the temperature dependence of the resistance oscillation stems from the growth of the Landau level broadening due to the enhancement of acoustic phonon scattering with increasing lattice temperature. The calculated temperature variation of the oscillation agrees well with experimental observations.

Microwave-induced electron heating in the regime of radiation-induced magnetoresistance oscillations

“…According to theory, [31,34,36]steady state microwave excitation can heat a high mobility two-dimensional electron system. The energy gain from the radiation field is balanced by energy loss to the lattice by electron-phonon scattering.…”

“…A further topic of experimental interest is to examine the possibility of electron heating, as theory has, [31,34,36] in consistency with common experience, indicated the possibility of microwave-induced electron heating in the high mobility 2DES in the regime of the radiation-induced magnetoresistance oscillations. Not surprisingly, under steady state microwave excitation, the 2DES can be expected to absorb energy from the radiation field.…”

Transport equation for the two-dimensional electron liquid under microwave radiation and a magnetic field: Explanation for the zero-resistance state

“…Most of the theoretical work suggests that the origin of the ZRS is closely related to a negativeresistance instability that occurs in the system due to the combined effect of quantized Landau levels and photonassisted scattering. [3][4][5][6][7]12 It was proposed that the ZRS can be explained if the current-dependent resistance of the system which becomes negative at small current ͑for strong enough microwave radiation͒ becomes positive again when the current j ជ becomes large enough. [3][4][5][6][7] The above physics was put together phenomenologically into an equation…”

“…[3][4][5][6][7]12 It was proposed that the ZRS can be explained if the current-dependent resistance of the system which becomes negative at small current ͑for strong enough microwave radiation͒ becomes positive again when the current j ជ becomes large enough. [3][4][5][6][7] The above physics was put together phenomenologically into an equationwhere R͓j͔ is a phenomenological current-dependent resistance which is negative at j = 0, increases as a function of j and passes through zero at ͉j ជ ͉ = j o , 7 E ជ d is the applied dc electric field and H is the ordinary Hall resistivity. It was suggested that Eq.…”

“…The discovery of the zero-resistance states ͑ZRS͒ in two dimensional electron gas under uniform magnetic field 1,2 and microwave radiation has triggered a lot of theoretical [3][4][5][6][7][8][9]12 and experimental activities 10,11 to understand the origin of this nontrivial state. Most of the theoretical work suggests that the origin of the ZRS is closely related to a negativeresistance instability that occurs in the system due to the combined effect of quantized Landau levels and photonassisted scattering.…”