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Solid-state lighting is a rapidly evolving technology, now virtually certain to someday displace traditional lighting in applications ranging from the lowest-power spot illuminator to the highest-power area illuminator. Moreover, it has considerable headroom for continued evolution even after this initial displacement. In this paper, we present a high-level overview of solid-state lighting, with an emphasis on white lighting suitable for general illumination. We characterize in detail solid-state lighting's past and potential-future evolution using various performance and cost metrics, with special attention paid to inter-relationships between these metrics imposed by human factors, technology, and economic considerations.

Solid-state lighting is a rapidly evolving, emerging technology whose efficiency of conversion of electricity to visible white light is likely to approach 50% within the next several years. This efficiency is significantly higher than that of traditional lighting technologies, giving solid-state lighting the potential to enable significant reduction in the rate of world energy consumption. Further, there is no fundamental physical reason why efficiencies well beyond 50% could not be achieved, which could enable even more significant reduction in world energy usage. In this article, we discuss in some detail: (a) the several approaches to inorganic solid-state lighting that could conceivably achieve “ultra-high,” 70% or greater, efficiency, and (b) the significant research questions and challenges that would need to be addressed if one or more of these approaches were to be realized.

We study the influence of a normal magnetic field on the 0.7 feature exhibited by quantum point contacts (QPCs). The magnetic field is used to induce the formation of edge states whose spin splitting and spatial separation can be varied directly via the applied field. By appropriate control of the gate voltage, the QPC can be configured so that its conductance is determined by the two spin-resolved edge states of the lowest Landau level, mimicking the two-channel picture that has been suggested in discussions of the 0.7 feature. Under these conditions, a clear 0.7 feature is only observed at weak magnetic fields, where any spin gap is small and the two edge states are strongly overlapping. A similar feature is also seen at high magnetic fields, but only once the temperature is increased such that the thermal energy is comparable to the size of the spin gap. The connection of these results to the processes that lead to the 0.7 feature is discussed.

Electron spin resonance (ESR) and electron-nuclear double resonance experiments were performed in the 2D electron systems of GaAs/Al x Ga 1− x As quantum well and heterojunction samples in the vicinity of the unity filling factor in the regime of the quantum Hall effect. As is well known, the ESR response is strongly affected by the local nuclear fields induced by dynamic nuclear polarization. The peculiar resistance responses resulting from dynamic nuclear polarization and NMR were numerically simulated on the basis of the rate equation for the Zeeman order of nuclei in the vicinity of the 2D electron system. The simulations, which include the nuclear spin diffusion, provide an opportunity to visualize the propagation of the nuclear spin polarization into the Al x Ga 1− x As barriers of the quantum wells.

We investigate the linear transport properties of quantum point contacts (QPCs) whose symmetry is deliberately broken in a controlled manner. The devices that we study consist of a conventional split-gate QPC, which is modified by the inclusion of an additional perturbing gate that is used to modulate the electron density on one side of the device. As the voltage applied to this 'finger gate' is varied, we observe several reproducible features below the last integer plateau, as well as strong modifications of the integer-plateau staircase. Self-consistent calculations, performed for the exact device structure utilized in experiment, suggest that these features are related to the ability of the finger gate to strongly disrupt the symmetry of the QPC, reducing the electron density significantly on one side of the device. We discuss these results within the context of recent models for many-body electron transport in QPCs.

We demonstrate the presence of a resonant interaction between a pair of coupled quantum wires, which are realized in the ultra-high mobility two-dimensional electron gas of a GaAs/AlGaAs quantum well. Measuring the conductance of one wire, as the width of the other is varied, we observe a resonant peak in its conductance that is correlated with the point at which the swept wire pinches off. We discuss this behaviour in terms of recent theoretical predictions concerning local spin-moment formation in quantum wires.

We demonstrate the presence of a resonant interaction between a pair of coupled quantum wires, which are formed in the ultrahigh mobility two-dimensional electron gas of a GaAs/AlGaAs quantum well. The coupled-wire system is realized by an extension of the split-gate technique, in which bias voltages are applied to Schottky gates on the semiconductor surface, to vary the width of the two quantum wires, as well as the strength of the coupling between them. The key observation of interest here is one in which the gate voltages used to define one of the wires are first fixed, after which the conductance of this wire is measured as the gate voltage used to form the other wire is swept. Over the range of gate voltage where the swept wire pinches off, we observe a resonant peak in the conductance of the fixed wire that is correlated precisely to this pinchoff condition. In this paper, we present new results on the current- and temperature-dependence of this conductance resonance, which we suggest is related to the formation of a local moment in the swept wire as its conductance is reduced below 2e/sup 2//h.

While quantized conductance steps in short quantum wires are understood through a single electron picture, additional structure often observed in high-quality one-dimensional systems near g=0.7×(2e2/h) is commonly interpreted as arising due to many-body interactions. Most studies of conductance structure below 2e2/h use short one-dimensional wires where transport is known to be ballistic. We report transport measurements for both short (0.5 μm) and long (5 μm) quantum wires, and use both conductance and nonlinear transport to explore the behavior of one-dimensional wires.

An equivalent circuit model for the double-electron layer tunneling transistor (DELTT) integrated with an antenna is presented in this paper. This device is used basically for THz detection, and the antenna is used to efficiently couple THz radiation into the device for processing. Developing an equivalent circuit model is extremely helpful in matching the antenna to the device.

We study nonequilibrium DC and photon-assisted tunneling (PAT) of electrons between two weakly tunnel-coupled biased electron layers. The PAT current is related to the DC current. The line shape of the PAT current is studied as a function of the bias energy and the temperature. The contributions from the intrinsic screened electron–phonon and electron–electron scattering to the widths of the tunneling spectra are examined. Calculated DC tunneling current is compared with recent data.

This report describes the condition of the research environment at Sandia National Laboratories and outlines key environment improvement activities undertaken by the Office of the Chief Technology Officer and the Sandia Research Leadership Team during fiscal year 2013. The report also outlines Lab-level objectives related to the research environment for fiscal year 2014.

We report on a new class of magnetoresistance oscillations observed in a high-mobility two-dimensional electron gas (2DEG) in GaAs-Al$_x$Ga$_{1-x}$As heterostructures. Appearing in a weak magnetic field ($B, Comment: 4 pages, RevTex4, 4 figures

Continuous and time-resolved magnetophotoluminescence measurements of three $\mathrm{GaAs}/{\mathrm{Al}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{As}$ heterostructures have been made in high magnetic fields. The spectra revealed the presence of a singlet and two triplet states (the so-called ``bright'' and ``dark'' states) of the negatively charged magnetoexciton, in addition to the neutral exciton. For an asymmetrically doped single quantum well sample, the singlet and the dark triplet states converge (and possibly cross) at a field of about 40 T. The two single heterojunction samples on the other hand show no such convergence, and the singlet remains the fundamental state at least in fields to 60 T. The lifetimes of the charged magnetoexcitons increased linearly with field, whereas the neutral exciton was essentially field independent. The results clarify earlier experimental studies, and provide a confirmation of a recent theory of the behavior of charged magnetoexcitons in magnetic fields by Wojs et al. [Phys Rev. B 62, 4630 (2000)].

We study the low-temperature in-plane magnetoconductance of vertically coupled double quantum wires. Using a novel flip-chip technique, the wires are defined by two pairs of mutually aligned split gates on opposite sides of a ≤ 1 micron thick AlGaAs/GaAs double quantum well heterostructure. We observe quantized conductance steps due to each quantum well and demonstrate independent control of each 1D wire. A broad dip in the magnetoconductance at ∼ 6 T is observed when a magnetic field is applied perpendicular to both the current and growth directions. This conductance dip is observed only when 1D subbands are populated in both the top and bottom constrictions. This data is consistent with a counting model whereby the number of subbands crossing the Fermi level changes with field due to the formation of an anticrossing in each pair of 1D subbands.

We report the results of polarized magneto-photoluminescence (MPL) measurements on a high mobility modulation-doped GaAs/AlGaAs single quantum well. The magnetic field was varied between 0 and 60 T. The appearance of a doublet structure in the heavy-hole magneto-exciton in the high field regime was interpreted as an indication for enhanced electron–hole exchange interaction induced by the confinement. The effective g -factor of the electron determined from the Zeeman splitting was 3.7 times higher than the bulk value.

This paper presents a study of the enhancement of the Zeeman energy of two-dimensional (2D) conduction electrons near the $\ensuremath{\nu}=1$ filling factor of the quantum Hall effect by optical dynamic nuclear polarization. The change in the Zeeman energy is determined from the Overhauser shift of the transport detected electron spin resonance in GaAs/${\mathrm{Al}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{As}$ multiquantum wells. In a separate experiment the NMR signal enhancement factor is obtained by radio frequency detected nuclear magnetic resonance under similar conditions in the same sample. These measurements afford an estimation of the hyperfine coupling constant between the nuclei and 2D conduction electrons.

The propagation direction of fractional quantum Hall effect (FQHE) edge states has been investigated experimentally via the symmetry properties of the multi-terminal capacitances of a two-dimensional electron gas. Although strong asymmetries with respect to zero magnetic field appear, no asymmetries with respect to even denominator Landau level filling factor ν are seen. This indicates that current-carrying FQHE edge states propagate in the same direction as integer QHE edge states. In addition, anomalous capacitance features, indicative of enhanced bulk conduction, are observed at ν= 1 2 and 3 2 .

The authors report on their recent experimental studies of vertically-coupled quantum point contacts subject to in-plane magnetic fields. Using a novel flip-chip technique, mutually aligned split gates on both sides of a sub micron thick double quantum well heterostructure define a closely-coupled pair of ballistic one-dimensional (1D) constrictions. They observe quantized conductance steps due to each quantum well and demonstrate independent control of each ID constriction width. In addition, a novel magnetoconductance feature at {approximately}6 T is observed when a magnetic field is applied perpendicular to both the current and growth directions. This conductance dip is observed only when 1D subbands are populated in both the top and bottom constrictions. This data is consistent with a counting model whereby the number of subbands crossing the Fermi level changes with field due to the formation of an anticrossing in each pair of 1D subbands.

We study the low-temperature in-plane magnetoresistance of tunnel-coupled quasi-one-dimensional quantum wires. The wires are defined by two pairs of mutually aligned split gates on opposite sides of a < 1 micron thick AlGaAs/GaAs double quantum well heterostructure, allowing independent control of their widths. In the ballistic regime, when both wires are defined and the field is perpendicular to the current, a large resistance peak at ~6 Tesla is observed with a strong gate voltage dependence. The data is consistent with a counting model whereby the number of subbands crossing the Fermi level changes with field due to the formation of an anticrossing in each pair of 1D subbands.

The transport properties of a quasi-three-dimensional, 200-layer quantum-well structure are investigated at integer filling in the quantum Hall state, concomitant with the chiral edge state condition. We find that the transverse magnetoresistance R{sub xx}, the Hall resistance R{sub xy}, and the vertical resistance R{sub zz} all follow a similar behavior with {ital both} temperature and in-plane magnetic field. A general characteristic of the influence of increasing in-plane field B{sub in} is that the quantization condition first improves, but above a critical value B{sub in}{sup C}, the quantization is systematically removed. We consider the interplay of the chiral edge state transport and the bulk (quantum Hall) transport properties. This mechanism may arise from the competition of the cyclotron energy with the superlattice band-structure energies. A comparison of the results with existing theories of the chiral edge state transport with in-plane field is also discussed. {copyright} {ital 1999} {ital The American Physical Society}

A new method for measuring the spin of the electrically charged ground-state excitations in the quantum Hall effect is proposed and demonstrated for the first time for GaAs/AlGaAs multiquantum wells. The method is based on the nuclear spin-orientation dependence of the two-dimensional direct-current conductivity in the quantum Hall regime due to the nuclear hyperfine interaction. We use this method to determine the spin of the electrically charged excitations of the ground state at filling factor = 1.

The effect of the nuclear hyperfine interaction on the dc conductivity of 2D electrons under quantum Hall effect conditions at filling factor v= 1 is observed for the first time. The local hyperfine field enhanced by dynamic nuclear polarization is monitored via the Overhauser shift of the 2D conduction electron spin resonance in AlGaAs/GaAs multiquantum-well samples. The experimentally observed change in the dc conductivity resulting from dynamic nuclear polarization is in agreement with a thermal activation model incorporating the Zeeman energy change due to the hyperfine interaction. The relaxation decay time of the dc conductivity is, within experimental error, the same as the relaxation time of the nuclear spin polarization determined from the Overhauser shift. These findings unequivocally establish the nuclear spin origins of the observed conductivity change.

We demonstrate the double electron layer tunnelling transistor (DELTT), based on the gate control of two-dimensional-two-dimensional tunnelling in a double quantum well. Unlike previously proposed resonant tunnelling transistors, the DELTT is entirely planar and can be easily fabricated in large numbers. At 1.5 K we demonstrate peak-to-background ratios of :1 in source-drain conductance versus gate voltage and peak-to-valley ratios of :1 in the source-drain current versus source-drain voltage. Using a single DELTT in series with a load resistor, we demonstrate low-power bistable memories at 1.5 K. We also demonstrate a unipolar complementary static RAM by connecting two DELTTs in series.

We describe the first demonstration of dual-side electron beam lithography in achieving independent submicron gating in double quantum well devices. The technique utilizes the epoxy-bond and stop-etch process to remove the substrate material which allows the backside gates to be placed in close proximity (less than 1 m) to the frontside gates. The use of electron beam lithography allows both the definition of submicron features and the precise alignment of the front and back features to each other. We have applied this technique to the fabrication of double quantum point contacts on coupled AlGaAs/GaAs double quantum wells. Low-temperature transport measurements clearly show the formation of coupled, independently controllable mesoscopic structures in each of the two quantum wells.

We present a linear-response theory of magneto-quantum-resistance oscillations of the in-plane resistances ${R}_{\mathrm{xx}}$ and ${R}_{\mathrm{yy}}$ in two coupled quasi-two-dimensional electron layers in tilted magnetic fields $\mathbf{B}{=(B}_{\ensuremath{\parallel}}{,B}_{\ensuremath{\perp}}),$ and explain recent data from ${\mathrm{G}\mathrm{a}\mathrm{A}\mathrm{s}/\mathrm{A}\mathrm{l}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{As}$ double quantum wells. In this system, the electrons are in the two tunnel-split ground sublevels. The cyclotron masses of the two orbits on the Fermi surface have opposite dependences on the in-plane field ${B}_{\ensuremath{\parallel}}:$ one increases monotonically, while the other decreases as a function of ${B}_{\ensuremath{\parallel}}$ in the regime of interest. As a result, the rungs of one Landau ladder sweep up through the Fermi level, while those of the other Landau ladder sweep down when ${B}_{\ensuremath{\parallel}}$ is increased at a fixed perpendicular field ${B}_{\ensuremath{\perp}}.$ Ridges are obtained in the three-dimensional plots of both ${R}_{\mathrm{xx}}$ and ${R}_{\mathrm{yy}}$ and the density of states versus ${(B}_{\ensuremath{\parallel}}{,B}_{\ensuremath{\perp}})$ due to Fermi-level crossing by the rungs of the Landau ladders. Giant peaks are obtained when two ridges intersect each other. The ${(B}_{\ensuremath{\parallel}}{,B}_{\ensuremath{\perp}})$ dependence of ${R}_{\mathrm{xx}}$ as well as theoretical evidence of magnetic breakdown yields good agreement with recent data from ${\mathrm{G}\mathrm{a}\mathrm{A}\mathrm{s}/\mathrm{A}\mathrm{l}}_{x}{\mathrm{Ga}}_{1\ensuremath{-}x}\mathrm{As}$ double quantum wells.

We investigate the transport properties of an extremely-coupled Al{sub x}Ga{sub 1{minus}x}As/GaAs double quantum well subject to in-plane magnetic fields B{sub {parallel}}. The coupling is sufficiently strong that the symmetric-antisymmetric gap energy {Delta}{sub SAS} is larger than the Fermi energy E{sub F}. Thus for all B{sub {parallel}} only the lower-energy dispersion branch is occupied. In contrast to systems where {Delta}{sub SAS}{lt}E{sub F}, we find: (1) only a single feature in the magnetoresistance, a maximum; (2) a monotonic increase in the cyclotron mass to roughly double the GaAs band mass; and (3) a monotonically increasing Fermi-surface orbit area. These experimental results agree well with our theoretical calculations. thinsp {copyright} {ital 1998} {ital The American Physical Society}

By measuring longitudinal resistance, we map the Landau level spectra of double quantum wells as a function of both parallel ( B ‖ ) and perpendicular ( B ⊥ ) magnetic fields. In this continuously tunable highly non-parabolic system, the cyclotron masses of the two Fermi surface orbits change in opposite directions with B ‖ . This causes the two corresponding ladders of Landau levels formed at finite B ⊥ to exhibit multiple crossings. We also observe a third set of Landau levels, independent of B ‖ , which arise from magnetic breakdown of the Fermi surface. Both semiclassical and full-quantum mechanical calculations show good agreement with the data.

We report reflectivity measurements at 810 nm wavelength on GaAs/GaAlAs multiple quantum wells and NbSe2 layers at 75 K up to magnetic fields of 800 T. In the GaAs system, we observed in two separate measurements new, reproducible oscillatory phenomena in the reflectivity between 30 and 800 T, and in a third measurement on 2H-NbSe2 we observed a decrease in reflectivity of about 50% above 200 T, with some additional evidence for oscillatory behavior. We discuss these measurements based on the expected behavior in terms of their known physical properties, and consider future prospects for the application of optical methods to study condensed matter physics under these extremes.

We experimentally determine the propagation direction of fractional quantum Hall effect (FQHE) edge states via the symmetry properties of the multiterminal capacitances of two dimensional electron gases. Although strong asymmetries with respect to zero magnetic field appear, no asymmetries with respect to even denominator Landau level filling factor {nu} are seen. This indicates that current-carrying FQHE edge states propagate in the same direction as integer QHE edge states, consistent with a composite fermion gauge effective electric field. We also observe anomalous capacitance features indicative of enhanced bulk conduction at {nu}=1/2 , 3/2 , and 3/4 . {copyright} {ital 1997} {ital The American Physical Society}

By measuring longitudinal resistance, the authors map the Landau level spectra of double quantum wells as a function of both parallel (B{sub {parallel}}) and perpendicular (B{sub {perpendicular}}) magnetic fields. In this continuously tunable highly non-parabolic system, the cyclotron masses of the two Fermi surface orbits change in opposite directions with B{sub {parallel}}. This causes the two corresponding ladders of Landau levels formed at finite B{sub {perpendicular}} to exhibit multiple crossings. They also observe a third set of landau levels, independent of B{sub {parallel}}, which arise from magnetic breakdown of the Fermi surface. Both semiclassical and full quantum mechanical calculations show good agreement with the data.

Technologies for artificial lighting, as illustrated on the left side of Fig. 2.1, have made tremendous progress over the centuries: from fire, with an efficiency of about a tenth of a percent; to incandescent lamps, with an efficiency of about 4 %; to gas discharge lamps, with an efficiency of about 20 %; and soon to solid-state lighting (SSL), with efficiencies that in principle could approach 100 %.

The epoxy bond and stop-etch (EBASE) technique enables both the frontside and the backside processing of very thin (∼3000A) GaAs/AlGaAs epitaxial layer structures. Using this technique, a conventionally processed epitaxial layer structure is inverted and epoxied to a new host substrate. The original substrate is removed leaving only the original epitaxial structure expoxied to the host substrate. The exposed backside of the epitaxial structure may then be processed. Because the structures fabricated using this technique are so thin, mesas, Schottky gates, and ohmic contacts may be defined in close proximity both above and below the active device layers.

We report on our studies of magnetic breakdown (MB) in coupled GaAs/Al 0.3 Ga 0.7 As double quantum wells (DQWs) subject to crossed magnetic fields. MB is a failure of semiclassical theory that occurs when a magnetic field causes electrons to tunnel across a gap in k -space from one Fermi surface (FS) branch to another. We study MB in a two-branch FS created by subjecting a DQW to an in-plane magnetic field ( B ∥ ). The principal effect of B ∥ is a distortion in the dispersion curve of the system, yielding a FS consisting of two components, a lens-shaped inner orbit and an hour-glass-shaped outer orbit. The perpendicular field ( B ⊥ ) causes Landau level formation and Shubnikov–de Haas (SdH) oscillations for each branch of the FS. At higher perpendicular fields MB occurs and electrons tunnel through k -space from one FS orbit to the other. MB is observed by noting which peaks are present in the Fourier power spectrum of the magnetoresistance versus 1/ B ⊥ at constant B ∥ . We observe MB in two DQW samples over a range of B ∥ .

A double quantum well (QW) subject to in-plane magnetic fields B∥ has the dispersion curves of its two QWs shifted in k-space. When the QWs are strongly coupled, an anticrossing and partial energy gap occur, yielding a tunable multi-component Fermi surface. We report measurements of the resultant features in the conductance, the capacitive density of states and giant deviations in the cyclotron effective masses.

Electrical operation of InGaN/GaN quantum-well heterostructure photonic crystal light-emitting diodes (PXLEDs) is demonstrated. A triangular lattice photonic crystal is formed by dry etching into the top GaN layer. Light absorption from the metal contact is minimized because the top GaN layers are engineered to provide lateral current spreading, allowing carrier recombination proximal to the photonic crystal yet displaced from the metal contact. The chosen lattice spacing for the photonic crystal causes Bragg scattering of guided modes out of the LED, increasing the extraction efficiency. The far-field radiation patterns of the PXLEDs are heavily modified and display increased radiance, up to ∼1.5 times brighter compared to similar LEDs without the photonic crystal.

Using an air-bridged gate, we have fabricated two closely spaced parallel quantum point contacts (QPC`s) in a GaAs-Al{sub {ital x}}Ga{sub 1{minus}{ital x}}As heterostructure. By biasing the gates appropriately, we have measured the magnetoresistance (MR) at low fields for both single and parallel point contacts. Assuming a parabolic potential, the MR of a single QPC can be quantitatively understood by a previous theory incorporating magnetic-field-suppressed backscattering. However, the MR of two QPC`s in parallel displays resistance peaks, implying a failure of Ohm`s law due to coupling between the channels. These resistance peaks are shown to be due to magnetic focusing of electrons from one channel into the other.

Large deviations are measured in the cyclotron effective mass {ital m}{sub {ital c}} near the recently observed partial energy gap arising in strongly coupled GaAs double quantum wells (QW`s) subject to in-plane magnetic fields {ital B}{sub {parallel}}. The energy gap results from an anticrossing of the two QW dispersion curves, shifted in {bold k} space relative to one another by {ital B}{sub {parallel}}. The severely distorted dispersion near the gap yields an {ital m}{sub {ital c}} repressed by more than a factor of 3 near the upper gap edge, and enhanced by {similar_to}50% near the lower gap edge. The data show excellent agreement with recent theoretical calculations.

We study the transport in a system of coupled quantum wires and show evidence for a resonant interaction that occurs whenever one of them is biased close to pinch off. Measuring the conductance of one of the wires, as the width of the other is varied, we observe a resonant peak in the conductance that is correlated to the point at which the other wire pinches off. The origin of this interaction remains undetermined at present, although its characteristics appear consistent with predictions that a correlated many-body state should form in narrow wires as their conductance vanishes.

We observe a strong modulation of the low temperature in-plane conductance [ital G][sub [parallel]] of coupled quantum wells (QWs) by an in-plane magnetic field [ital B][sub [parallel]], and attribute this to an anticrossing of the two QW dispersion curves. The anticrossing produces a partial energy gap, yielding large, [ital B][sub [parallel]]-tunable distortions in the Fermi surface and density of states. Sweeping [ital B][sub [parallel]] moves the energy gap through the Fermi level, with the upper and lower gap edges producing a sharp maximum and minimum in [ital G][sub [parallel]], in agreement with theoretical calculations. The gap energy is directly determined from the data.

Double-quantum-well field-effect transistors with a grating gate exhibit a sharply resonant, voltage tuned terahertz photoconductivity. The voltage tuned resonance is determined by the plasma oscillations of the composite structure. The resonant photoconductivity requires a double-quantum well but the mechanism whereby plasma oscillations produce changes in device conductance is not understood. The phenomenon is potentially important for fast, tunable terahertz detectors.

Low-magnetic field (B kG ) magnetoresistance oscillations (periodic in 1/ B ) have been observed in a high-mobility two-dimensional electron gas (2DEG). Such novel oscillations appear only in a limited temperature range (approximately, 2 K K ). The effect is attributed to magnetophonon resonance of 2DEG with thermally excited leaky interface-acoustic phonons. Results from Fourier analysis of the temperature dependence data are consistent with a model in which two branches of phonon modes contribute to the resonance.

In the regime of the fractional quantum Hall effect, with Landau filling ν

In 1957, Sandia National Laboratories (Sandia) initiated its first programs in fundamental science, in support of its primary nuclear weapons mission. In 1974, Sandia initiated programs in fundamental science supported by the Department of Energy's Office of Science (DOE-SC). These latter programs have grown to the point where, today in 2011, support of Sandia's programs in fundamental science is dominated by that Office. In comparison with Sandia's programs in technology and mission applications, however, Sandia's programs in fundamental science are small. Hence, Sandia's fundamental science has been strongly influenced by close interactions with technology and mission applications. In many instances, these interactions have been of great mutual benefit, with synergies akin to a positive 'Casimir's spiral' of progress. In this report, we review the history of Sandia's fundamental science programs supported by the Office of Science. We present: (a) a technical and budgetary snapshot of Sandia's current programs supported by the various suboffices within DOE-SC; (b) statistics of highly-cited articles supported by DOE-SC; (c) four case studies (ion-solid interactions, combustion science, compound semiconductors, advanced computing) with an emphasis on mutually beneficial interactions between science, technology, and mission; and (d) appendices with key memos and reminiscences related to fundamental science at Sandia.

Previous resistively detected NMR (RDNMR) studies on the $\ensuremath{\nu}\ensuremath{\approx}1$ quantum Hall state have reported a ``dispersionlike'' line shape and extremely short nuclear-spin-lattice relaxation times, observations which have been attributed to the formation of a skyrme lattice. Here we examine the evolution of the RDNMR line shape and nuclear-spin relaxation for Zeeman:Coulomb energy ratios ranging from 0.012 to 0.036. According to theory, suppression of the skyrme crystal, along with the associated Goldstone mode nuclear-spin-relaxation mechanism, is expected at the upper end of this range. However, we find that the anomalous line shape persists at high Zeeman energy, and only a modest decrease in the RDNMR-detected nuclear-spin-relaxation rate is observed.