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

Transport study of Berry's phase, the resistivity rule, and quantum Hall effect in graphite

Transport measurements indicate strong oscillations in the Hall-,$R_{xy}$, and the diagonal-, $R_{xx}$, resistances and exhibit Hall plateaus at the lowest temperatures, in three-dimensional Highly Oriented Pyrolytic Graphite (HOPG). At the same time, a comparative Shubnikov-de Haas-oscillations-based Berry's phase analysis indicates that graphite is unlike the GaAs/AlGaAs 2D electron system, the 3D n-GaAs epilayer, semiconducting $Hg_{0.8}Cd_{0.2}Te$, and some other systems. Finally, we observe the transport data to follow $B\times dR_{xy}/dB \approx - \Delta R_{xx}$. This feature is consistent with the observed relative phases of the oscillatory $R_{xx}$ and $R_{xy}$.Comment: 5 pages, 4 figure

Modeling Crop Yield Distributions from Small Samples

Accurately modeling crop yield distributions is important for estimation of crop insurance premiums and farm risk-management decisions. A major challenge in the modeling has been due to small sample size. This study evaluated potentials of L-moments, a recent concept in mathematical statistics, in modeling crop yield distribution. Five candidate distributions were ranked for describing the wheat yields. The selected distribution was robust for small sample and was invariant to de-trending. The result was consistent with that from the maximum likelihood and goodness-of-fit method.Crop Production/Industries,