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“Background Transport excited by radiation in a two-dimensional electron system selleck screening library (2DES) has been always [1–3] a central topic in basic and especially in applied research. In the last decade, it was discovered that when a high mobility 2DES in a low and perpendicular magnetic field (B) is irradiated, mainly with microwaves (MW), some striking effects are revealed: radiation-induced magnetoresistance (R x x ) oscillations and zero resistance states (ZRS) [4, 5]. Different theories and experiments have been proposed to explain these effects [6–18], but the

physical origin is still being questioned. An interesting and challenging experimental results, recently obtained [19] and as intriguing as ZRS, consists in a strong resistance spike which shows up far off-resonance. It occurs at twice the cyclotron frequency, w≈2w c[19], where w is the radiation frequency, and w c is the cyclotron

frequency. Remarkably, the only different feature in these experiments [19] is the use of ultraclean samples with mobility μ ∼ 3 × 107 cm2 V s-1 and lower temperatures T∼0.4 K. Yet, for the previous ‘standard’ experiments and samples [4, 5], mobility is lower (μ < 107 cm2 V s-1) and T higher (T ≥ 1.0 K). In this letter, we theoretically study this radiation-induced R xx spike, applying the theory developed by the authors, the radiation-driven electron orbits model[6–10, 20–25]. According to the theory, when a Hall bar is illuminated, the electron orbit centers perform a classical trajectory consisting in a classical forced Sorafenib chemical structure harmonic motion along the direction of the current at the radiation frequency, w. This motion is damped by the interaction of electrons with the lattice ions and with the consequent emission of acoustic phonons. We extend this model to an ultraclean sample, where the Landau levels (LL), which in principle are broadened by scattering, become Parvulin very narrow. This implies an increasing number of states at the center of the LL sharing a similar energy. In between LL, the opposite happens: the density of states dramatically decreases.

This will eventually XAV-939 datasheet affect the measured stationary current and R x x . We obtain that in the ultraclean scenario, the measured current on average is the same as the one obtained in a sample with full contribution to R x x but delayed as if it were irradiated with a half MW frequency (w/2). Accordingly, the cyclotron resonance is apparently shifted to a new B-position around w ≈ 2w c. Methods The radiation-driven electron orbits model was developed to explain the R x x response of an irradiated 2DEG at low magnetic field [6–10, 20–25]. The corresponding time-dependent Schrödinger equation can be exactly solved. Thus, we first obtain an exact expression of the electronic wave vector for a 2DES in a perpendicular B, a DC electric field, and radiation: where ϕ n is the solution for the Schrödinger equation of the unforced quantum harmonic oscillator.