Photo-excited zero-resistance states in the GaAs/AlGaAs system

The microwave-excited high mobility two-dimensional electron system exhibits, at liquid helium temperatures, vanishing resistance in the vicinity of $B = [4/(4j+1)] B_{f}$, where $B_{f} = 2\pi\textit{f}m^{*}/e$, m$^{*}$ is an effective mass, e is the charge, and \textit{f} is the microwave frequency. Here, we summarize some experimental results.Comment: 7 color figures, 5 page

Spin characterization and control over the regime of radiation-induced zero-resistance states

Over the regime of the radiation-induced zero-resistance states and associated oscillatory magnetoresistance, we propose a low magnetic field analog of quantum-Hall-limit techniques for the electrical detection of electron spin- and nuclear magnetic- resonance, dynamical nuclear polarization via electron spin resonance, and electrical characterization of the nuclear spin polarization via the Overhauser shift. In addition, beats observed in the radiation-induced oscillatory-magnetoresistance are developed into a method to measure and control the zero-field spin splitting due to the Bychkov-Rashba and bulk inversion asymmetry terms in the high mobility GaAs/AlGaAs system.Comment: IEEE Transactions in Nanotechnology (to be published); 10 pages, 10 color figure

Radiation-induced zero-resistance states with resolved Landau levels

The microwave-photoexcited high mobility GaAs/AlGaAs two-dimensional electron system exhibits an oscillatory-magnetoresistance with vanishing resistance in the vicinity of magnetic fields $B = [4/(4j+1)] B_{f}$, where $B_{f} = 2\pi\textit{f}m^{*}/e$, m$^{*}$ is an the effective mass, e is the charge, \textit{f} is the microwave frequency, and $j$ =1,2,3... Here, we report transport with well-resolved Landau levels, and some transmission characteristics.Comment: 4 pages, 3 color figures, published versio

Temperature effects on microwave-induced resistivity oscillations and zero resistance states in 2D electron systems

In this work we address theoretically a key issue concerning microwave-induced longitudinal resistivity oscillations and zero resistance states, as is tempoerature. In order to explain the strong temperature dependence of the longitudinal resistivity and the thermally activated transport in 2DEG, we have developed a microscopic model based on the damping suffered by the microwave-driven electronic orbit dynamics by interactions with the lattice ions yielding acoustic phonons. Recent experimental results show a reduction in the amplitude of the longitudinal resistivity oscillations and a breakdown of zero resistance states as the radiation intensity increases. In order to explain it we have included in our model the electron heating due to large microwave intensities and its effect on the longitudinal resistivity.Comment: 4 pages and 4 figures. Accepted in Phys Rev

Observation of a uniform temperature dependence in the electrical resistance across the structural phase transition in thin film vanadium oxide (VO2VO_{2})

An electrical study of thin $VO_{2}$ films in the vicinity of the structural phase transition at $68^{0}C$ shows (a) that the electrical resistance $R$ follows $log (R)$ $\propto$ $-T$ over the $T$-range, $20 < T < 80 ^{0}C$ covering both sides of the structural transition, and (b) a history dependent hysteresis loop in $R$ upon thermal cycling. These features are attributed here to transport through a granular network.Comment: 3 pages, 3 color figure

Demonstration of a 1/4 cycle phase shift in the radiation-induced oscillatory-magnetoresistance in GaAs/AlGaAs devices

We examine the phase and the period of the radiation-induced oscillatory-magnetoresistance in GaAs/AlGaAs devices utilizing in-situ magnetic field calibration by Electron Spin Resonance of DiPhenyl-Picryl-Hydrazal. The results confirm a $f$-independent 1/4 cycle phase shift with respect to the $hf = j\hbar\omega_{c}$ condition for $j \geq 1$, and they also suggest a small ($\approx$ 2%) reduction in the effective mass ratio, $m^{*}/m$, with respect to the standard value for GaAs/AlGaAs devices.Comment: 4 pages, 4 color figure

Observation of linear-polarization-sensitivity in the microwave-radiation-induced magnetoresistance oscillations

In the quasi two-dimensional GaAs/AlGaAs system, we investigate the effect of rotating \textit{in-situ} the electric field of linearly polarized microwaves relative to the current, on the microwave-radiation-induced magneto-resistance oscillations. We find that the frequency and the phase of the photo-excited magneto-resistance oscillations are insensitive to the polarization. On the other hand, the amplitudes of the magnetoresistance oscillations are remarkably responsive to the relative orientation between the microwave antenna and the current-axis in the specimen. The results suggest a striking linear-polarization-sensitivity in the radiation-induced magnetoresistance oscillations.Comment: 4 figures, 5 page