Thermal Mechanism of Absolute Negative Conductivity in Two-Dimensional Electron Systems.pdf

a r X i v : c o n d - m a t / 0 3 0 5 4 8 4 v 1 [ c o n d - m a t .m e s - h a l l ] 2 1 M a y 2 0 0 3 APS/123-QED Thermal Mechanism of Absolute Negative Conductivity in Two-Dimensional Electron Systems V. Ryzhii? Computer Solid State Physics Laboratory, University of Aizu, Aizu-Wakamatsu 965-8580, Japan (Dated: February 2, 2008) We calculate the dissipative dc conductivity of a two-dimensional electron system in a magnetic field for the situation when its effective temperature exceeds the temperature of the acoustic phonon system. We demonstrate that at sufficiently large difference between the electron and lattice temper- atures (sufficiently strong microwave radiation) the dissipative dc conductivity can become negative. As an illustration, the case of the electron heating by microwave radiation is considered. PACS numbers: PACS numbers: 73.40.-c, 78.67.-n, 73.43.-f I. INTRODUCTION Recent experimental studies of new types of magne- toresistance oscillations in a two-dimensional electron system (2DES) in a magnetic field [1, 2, 3, 4, 5], partic- ularly the observation of vanishing electrical resistance caused by microwave radiation, have stimulated exten- sive efforts to clarify the origin of the uncovered phe- nomena. The occurrence of the effect of the so-called zero-resistance states is closely associated with the effect of absolute negative conductivity (ANC) when the dissi- pative dc conductivity σ is negative [6, 7, 8]. Mechanisms of ANC in a 2DES subjected to a magnetic field un- der nonequilibrium conditions, in particular under irra- diation with microwaves, have been studied theoretically since the late 60s [9, 10, 11, 12, 13, 14, 15, 16, 17]. One can speculate that the photon-assisted impurity scatter- ing [11, 12, 13] is the main mechanism of ANC causing the zero-resistance states. Notwithstanding this, a revi- sion of alternate possible mechanisms of ANC may be of interest as well. In this paper, we show that ANC can occur owing to the electro