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Articles 1 - 8 of 8
Full-Text Articles in Physical Sciences and Mathematics
Temperature Dependence Of The Normal-Metal Aharonov-Bohm Effect, S. Washburn, C. P. Umbach, R. B. Laibowitz, Richard A. Webb
Temperature Dependence Of The Normal-Metal Aharonov-Bohm Effect, S. Washburn, C. P. Umbach, R. B. Laibowitz, Richard A. Webb
Faculty Publications
The amplitude of h/e periodic oscillations in the magnetoresistance of very small normal-metal (Au) rings, as well as the harmonic h/2e, have been studied as a function of temperature. The amplitudes depend on the temperature T roughly as T-1/2, as expected from the averaging of conduction channels in the absence of inelastic scattering, but may not be entirely consistent with this model. At the lowest T, the size of the fluctuations in the conductance is about ΔG∼e2/h, as predicted recently.
A Generalized Molien Function For Field Theoretical Hamiltonians, Jeffrey W. Felix, Dorian M. Hatch
A Generalized Molien Function For Field Theoretical Hamiltonians, Jeffrey W. Felix, Dorian M. Hatch
Faculty Publications
A generating function, or Molien function, the coefficients of which give the number of independent polynomial invariants in G, has been useful in the Landau and renormalization group theories of phase transitions. Here a generalized Molien function for a field theoretical Hamiltonian (with short-range interactions) of the most general form invariant in a group G is derived. This form is useful for more general renormalization group calculations. Its Taylor series is calculated to low order for the FGamma-2 representation of the space group R[3 bar]c and also for the l=1 (faithful) representation of SO(3).
Observation Of H/E Aharonov-Bohm Oscillations In Normal-Metal Rings, Richard A. Webb, S. Washburn, C. P. Umbach, R. B. Laibowitz
Observation Of H/E Aharonov-Bohm Oscillations In Normal-Metal Rings, Richard A. Webb, S. Washburn, C. P. Umbach, R. B. Laibowitz
Faculty Publications
Magnetoresistance oscillations periodic with respect to the flux h/e have been observed in submicron-diameter Au rings, along with weaker h/2e oscillations. The h/e oscillations persist to very large magnetic fields. The background structure in the magnetoresistance was not symmetric about zero field. The temperature dependence of both the amplitude of the oscillations and the background are consistent with the recent theory by Stone.
Effects Of Dissipation And Temperature On Macroscopic Quantum Tunneling, S. Washburn, Richard A. Webb, R. F. Voss, S. M. Faris
Effects Of Dissipation And Temperature On Macroscopic Quantum Tunneling, S. Washburn, Richard A. Webb, R. F. Voss, S. M. Faris
Faculty Publications
Measurements of the tunneling rate Γ out of the zero-voltage state for several Nb edge junctions with differing shunt capacitances are described. At zero temperature, increasing the shunt capacitance lowers Γ in agreement with dissipative calculations of the macroscopic-quantum-tunneling rate. As temperature increases, ln[Γ(T)/Γ(0)]∝T2 as recently predicted.
Origin Of The Peaked Structure In The Conductance Of One-Dimensional Silicon Accumulation Layers, Richard A. Webb, A. Hartstein, J. J. Wainer, A. B. Fowler
Origin Of The Peaked Structure In The Conductance Of One-Dimensional Silicon Accumulation Layers, Richard A. Webb, A. Hartstein, J. J. Wainer, A. B. Fowler
Faculty Publications
We have made extensive studies of the temperature, gate voltage, and electric field dependences of the conductance peaks in small silicon inversion layers in order to distinguish between resonant-tunneling models and a hopping model. We find that many of the peaks are consistent only with a hopping model, whereas some could be consistent with an early resonant-tunneling model. None of our structure is consistent with resonant tunneling if the recent formulation of Stone and Lee is correct.
Example Of A Group Action Determined Phase Transition, Jeffrey W. Felix, Dorian M. Hatch
Example Of A Group Action Determined Phase Transition, Jeffrey W. Felix, Dorian M. Hatch
Faculty Publications
The principles of the group action approach to structural phase transitions are outlined. It is assumed that all properties of the transition are determined by the action of a single physically irreducible represention of the space group of the more symmetric phase. We determine the isotropy groups using the image space of the representation. The free energy minima are determined to fourth order and to all orders using the results of Gufan and then compared. This theory is applied to Calcite (Roverline3c) to determine all possible continuous commensurate phase transitions.
New Shubnikov-De Haas Effects In A Two-Dimensional Electron-Hole System, S. Washburn, Richard A. Webb, E. E. Mendez, L. L. Chang, L. Esaki
New Shubnikov-De Haas Effects In A Two-Dimensional Electron-Hole System, S. Washburn, Richard A. Webb, E. E. Mendez, L. L. Chang, L. Esaki
Faculty Publications
We report the temperature dependence of the Shubnikov–de Haas oscillations from a two-dimensional electron-hole system in GaSb-InAs-GaSb quantum wells at very low temperatures. The samples are double heterostructures containing separate electron and hole layers. The oscillations arising from the electron layer behave regularly with temperature. Additional oscillations, characterized by strong temperature dependence, and relatively large peak widths are believed to arise from the presence of hole layers.
Quantum Electrodynamics Based On Self-Energy: Lamb Shift And Spontaneous Emission Without Field Quantization, A. O. Barut, Jean F. Van Huele
Quantum Electrodynamics Based On Self-Energy: Lamb Shift And Spontaneous Emission Without Field Quantization, A. O. Barut, Jean F. Van Huele
Faculty Publications
The theory of radiative processes in quantum theory is formulated on the basis of self-energy, in analogy to classical radiation theory, and is explicitly carried out for the calculation of the Lamb shift and spontaneous emission.