Orbitronics: the Intrinsic Orbital Hall Effect in p-Doped Silicon (open access)

Orbitronics: the Intrinsic Orbital Hall Effect in p-Doped Silicon

The spin Hall effect depends crucially on the intrinsic spin-orbit coupling of the energy band. Because of the smaller spin-orbit coupling in silicon, the spin Hall effect is expected to be much reduced. We show that the electric field in p-doped silicon can induce a dissipationless orbital current in a fashion reminiscent of the spin Hall effect. The vertex correction due to impurity scattering vanishes and the effect is therefore robust against disorder. The orbital Hall effect can lead to the accumulation of local orbital momentum at the edge of the sample, and can be detected by the Kerr effect.
Date: January 15, 2010
Creator: Bernevig, B.Andrei; Hughes, Taylor L.; Zhang, Shou-Cheng & /Stanford U., Phys. Dept.
Object Type: Article
System: The UNT Digital Library
Maxwell Equation for the Coupled Spin-Charge Wave Propagation (open access)

Maxwell Equation for the Coupled Spin-Charge Wave Propagation

We show that the dissipationless spin current in the ground state of the Rashba model gives rise to a reactive coupling between the spin and charge propagation, which is formally identical to the coupling between the electric and the magnetic fields in the 2 + 1 dimensional Maxwell equation. This analogy leads to a remarkable prediction that a density packet can spontaneously split into two counter propagation packets, each carrying the opposite spins. In a certain parameter regime, the coupled spin and charge wave propagates like a transverse 'photon'. We propose both optical and purely electronic experiments to detect this effect.
Date: January 15, 2010
Creator: Bernevig, B.Andrei; Yu, Xiaowei; Zhang, Shou-Cheng & /Stanford U., Phys. Dept.
Object Type: Article
System: The UNT Digital Library
Intrinsic Spin-Hall Effect in n-Doped Bulk GaAs (open access)

Intrinsic Spin-Hall Effect in n-Doped Bulk GaAs

We show that the bulk Dresselhauss (k{sup 3}) spin-orbit coupling term leads to an intrinsic spin-Hall effect in n-doped bulk GaAs, but without the appearance of uniform magnetization. The spin-Hall effect in strained and unstrained bulk GaAs has been recently observed experimentally by Kato et. al. [1]. We show that the experimental result is quantitatively consistent with the intrinsic spin-Hall effect due to the Dresselhauss term, when lifetime broadening is taken into account. On the other hand, extrinsic contribution to the spin-Hall effect is several orders of magnitude smaller than the observed effect.
Date: January 15, 2010
Creator: Bernevig, B.Andrei; Zhang, Shou-Cheng & /Stanford U., Phys. Dept.
Object Type: Report
System: The UNT Digital Library
Intrinsic Spin Hall Effect in the Two Dimensional Hole Gas (open access)

Intrinsic Spin Hall Effect in the Two Dimensional Hole Gas

We show that two types of spin-orbit coupling in the 2 dimensional hole gas (2DHG), with and without inversion symmetry breaking, contribute to the intrinsic spin Hall effect. Furthermore, the vertex correction due to impurity scattering vanishes in both cases, in sharp contrast to the case of usual Rashba coupling in the electron band. Recently, the spin Hall effect in a hole doped GaAs semiconductor has been observed experimentally by Wunderlich et al. From the fact that the life time broadening is smaller than the spin splitting, and the fact impurity vertex corrections vanish in this system, we argue that the observed spin Hall effect should be in the intrinsic regime.
Date: January 15, 2010
Creator: Bernevig, B.Andrei; Zhang, Shou-Cheng & /Stanford U., Phys. Dept.
Object Type: Article
System: The UNT Digital Library
Quantum Spin Hall Effect (open access)

Quantum Spin Hall Effect

The quantum Hall liquid is a novel state of matter with profound emergent properties such as fractional charge and statistics. Existence of the quantum Hall effect requires breaking of the time reversal symmetry caused by an external magnetic field. In this work, we predict a quantized spin Hall effect in the absence of any magnetic field, where the intrinsic spin Hall conductance is quantized in units of 2 e/4{pi}. The degenerate quantum Landau levels are created by the spin-orbit coupling in conventional semiconductors in the presence of a strain gradient. This new state of matter has many profound correlated properties described by a topological field theory.
Date: January 15, 2010
Creator: Bernevig, B.Andrei; Zhang, Shou-Cheng & /Stanford U., Phys. Dept.
Object Type: Article
System: The UNT Digital Library
Spin Splitting and Spin Current in Strained Bulk Semiconductors (open access)

Spin Splitting and Spin Current in Strained Bulk Semiconductors

We present a theory for two recent experiments in bulk strained semiconductors and show that a new, previously overlooked, strain spin-orbit coupling term may play a fundamental role. We propose simple experiments that could clarify the origin of strain-induced spin-orbit coupling terms in inversion asymmetric semiconductors. We predict that a uniform magnetization parallel to the electric field will be induced in the samples studied in for specific directions of the applied electric field. We also propose special geometries to detect spin currents in strained semiconductors.
Date: January 15, 2010
Creator: Bernevig, B.Andrei; Zhang, Shou-Cheng & /Stanford U., Phys. Dept.
Object Type: Article
System: The UNT Digital Library
CRS Issue Statement on Intelligence Policy (open access)

CRS Issue Statement on Intelligence Policy

This report contains the distinction between foreign and law enforcement intelligence that remain important when civil liberties and privacy rights of U.S. persons are involved.
Date: January 15, 2010
Creator: Best, Richard A., Jr.
Object Type: Report
System: The UNT Digital Library
The National Counterterrorism Center (NCTC)--Responsibilities and Potential Congressional Concerns (open access)

The National Counterterrorism Center (NCTC)--Responsibilities and Potential Congressional Concerns

This report looks at inadequacies present in the National Counterterrorism Center (NCTC) which prevent the Center from adequately performing its duty. These inadequacies include issues with agency organization, lack of resources, and a focus on threats from Yemen over domestic threats.
Date: January 15, 2010
Creator: Best, Richard A., Jr.
Object Type: Report
System: The UNT Digital Library
Nuclear Explosion Monitoring R&D Roadmap (open access)

Nuclear Explosion Monitoring R&D Roadmap

None
Date: January 15, 2010
Creator: Casey, L; Ziagos, J; Rodgers, A & Bell, W R
Object Type: Article
System: The UNT Digital Library
CRS Issue Statement on Medicare Reform (open access)

CRS Issue Statement on Medicare Reform

This report discusses about medicare and its spending that has been growing much faster than the general economy. It further discusses about congress's consideration on change on medicare expenditure by reducing provider payment.
Date: January 15, 2010
Creator: Davis, Patricia A.
Object Type: Report
System: The UNT Digital Library
CRS Issue Statement on Military Construction and Veterans Affairs Appropriations (open access)

CRS Issue Statement on Military Construction and Veterans Affairs Appropriations

The closing, reduction in scope, or expansion of military installations on domestic soil and overseas, the privatization of government-built military housing, the provision of benefits and medical care to eligible veterans, and the redeployment of military units to the United States from overseas garrisons have drawn congressional attention in recent sessions. The funds to support all of these activities are provided by the Military Construction, Veterans Affairs, and Related Agencies Appropriations Act debated annually in both chambers.
Date: January 15, 2010
Creator: Else, Daniel H.; Panangala, Sidath Viranga & Scott, Christine
Object Type: Report
System: The UNT Digital Library
Ferromagnetism in the Mott insulator Ba2NaOsO6 (open access)

Ferromagnetism in the Mott insulator Ba2NaOsO6

Results are presented of single crystal structural, thermodynamic, and reflectivity measurements of the double-perovskite Ba{sub 2}NaOsO{sub 6}. These characterize the material as a 5d1 ferromagnetic Mott insulator with an ordered moment of {approx} 0.2 {micro}B per formula unit and T{sub C} = 6.8(3) K. The magnetic entropy associated with this phase transition is close to Rln2, indicating that the quartet groundstate anticipated from consideration of the crystal structure is split, consistent with a scenario in which the ferromagnetism is associated with orbital ordering.
Date: January 15, 2010
Creator: Erickson, A. S.; Misra, S.; Miller, G. J.; Harrison, W. A.; Kim, J. M. & Fisher, I. R.
Object Type: Article
System: The UNT Digital Library
NATO Enlargement: Senate Advice and Consent (open access)

NATO Enlargement: Senate Advice and Consent

This report describes the provisions of the North Atlantic Treaty and of the original Senate debate in 1949 pertinent to enlargement and the procedures that have been followed for each subsequent enlargement proposal. It also discusses what the Senate did with respect to the reunification of Germany in 1990 and the implications of that event for Germany's membership in NATO.
Date: January 15, 2010
Creator: Garcia, Michael John
Object Type: Report
System: The UNT Digital Library
Research and Development (R&D) to Enhance Homeland Security: CRS Experts (open access)

Research and Development (R&D) to Enhance Homeland Security: CRS Experts

This report includes a table which provides access to names and contact information for CRS experts on policy concerns relating to research and development (R&D) to enhance homeland security.
Date: January 15, 2010
Creator: Gottron, Frank
Object Type: Report
System: The UNT Digital Library
100-KE REACTOR CORE REMOVAL PROJECT ALTERNATIVE ANALYSIS WORKSHOP REPORT (open access)

100-KE REACTOR CORE REMOVAL PROJECT ALTERNATIVE ANALYSIS WORKSHOP REPORT

On December 15-16, 2009, a 100-KE Reactor Core Removal Project Alternative Analysis Workshop was conducted at the Washington State University Consolidated Information Center, Room 214. Colburn Kennedy, Project Director, CH2M HILL Plateau Remediation Company (CHPRC) requested the workshop and Richard Harrington provided facilitation. The purpose of the session was to select the preferred Bio Shield Alternative, for integration with the Thermal Shield and Core Removal and develop the path forward to proceed with project delivery. Prior to this workshop, the S.A. Robotics (SAR) Obstruction Removal Alternatives Analysis (565-DLV-062) report was issued, for use prior to and throughout the session, to all the team members. The multidisciplinary team consisted ofrepresentatives from 100-KE Project Management, Engineering, Radcon, Nuclear Safety, Fire Protection, Crane/Rigging, SAR Project Engineering, the Department of Energy Richland Field Office, Environmental Protection Agency, Washington State Department of Ecology, Defense Nuclear Facility Safety Board, and Deactivation and Decommission subject matter experts from corporate CH2M HILL and Lucas. Appendix D contains the workshop agenda, guidelines and expectations, opening remarks, and attendance roster going into followed throughout the workshop. The team was successful in selecting the preferred alternative and developing an eight-point path forward action plan to proceed with conceptual design. Conventional Demolition …
Date: January 15, 2010
Creator: Harrington, R. A.
Object Type: Report
System: The UNT Digital Library
Short-term antibiotic treatment has differing long-term impacts on the human throat and gut microbiome (open access)

Short-term antibiotic treatment has differing long-term impacts on the human throat and gut microbiome

Antibiotic administration is the standard treatment for the bacterium Helicobacter pylori, the main causative agent of peptic ulcer disease and gastric cancer. However, the long-term consequences of this treatment on the human indigenous microbiota are relatively unexplored. Here we studied short- and long-term effects of clarithromycin and metronidazole treatment, a commonly used therapy regimen against H. pylori, on the indigenous microbiota in the throat and in the lower intestine. The bacterial compositions in samples collected over a four year period were monitored by analyzing the 16S rRNA gene using 454-based pyrosequencing and terminal-restriction fragment length polymorphism (T-RFLP). While the microbial communities of untreated control subjects were relatively stable over time, dramatic shifts were observed one week after antibiotic treatment with reduced bacterial diversity in all treated subjects in both locations. While the microbiota of the different subjects responded uniquely to the antibiotic treatment some general trends could be observed; such as a dramatic decline in Actinobacteria in both throat and feces immediately after treatment. Although the diversity of the microbiota subsequently recovered to resemble the pre treatment states, the microbiota remained perturbed in some cases for up to four years post treatment. In addition, four years after treatment high levels …
Date: January 15, 2010
Creator: Jakobsson, H.; Jernberg, C.; Andersson, A.F.; Sjolund-Karlsson, M.; Jansson, J.K. & Engstrand, L.
Object Type: Article
System: The UNT Digital Library
Iraq: Politics, Elections, and Benchmarks (open access)

Iraq: Politics, Elections, and Benchmarks

This report provides an overview of Iraq's political transition from the dictatorship of Saddam Hussein to a plural polity that encompasses varying sects and ideological and political factions. This report also addresses ongoing governmental instabilities and their causes, as well as U.S. concerns about possible Iranian influence in Iraq as U.S. forces depart the country.
Date: January 15, 2010
Creator: Katzman, Kenneth
Object Type: Report
System: The UNT Digital Library
Magic Doping Fractions in High-Temperature Superconductors (open access)

Magic Doping Fractions in High-Temperature Superconductors

We report hole-doping dependence of the in-plane resistivity {rho}{sub ab} in a cuprate superconductor La{sub 2-x}Sr{sub x}CuO{sub 4}, carefully examined using a series of high-quality single crystals. Our detailed measurements find a tendency towards charge ordering at particular rational hole doping fractions of 1/16, 3/32, 1/8, and 3/16. This observation appears to suggest a specific form of charge order and is most consistent with the recent theoretical prediction of the checkerboard-type ordering of the Cooper pairs at rational doping fractions x = (2m + 1)/2{sup n}, with integers m and n.
Date: January 15, 2010
Creator: Komiya, Seiki; Chen, Han-Dong; Zhang, Shou-Cheng & Ando, Yoichi
Object Type: Article
System: The UNT Digital Library
Hate Crime Legislation (open access)

Hate Crime Legislation

This report provides an overview of the hate crime debate, with background on current law and hate crime statistics, and a legislative history of hate crime prevention bills in recent Congresses. This report does not analyze the constitutional or other legal issues that often arise as part of the hate crime debate.
Date: January 15, 2010
Creator: Krouse, William J.
Object Type: Report
System: The UNT Digital Library
Older Displaced Workers in the Context of an Aging and Slowly Growing Population (open access)

Older Displaced Workers in the Context of an Aging and Slowly Growing Population

This report analyzes the labor market experiences of those older workers who have involuntarily lost long-held jobs for reasons unrelated to their own performance (e.g., veteran factory workers at plants closed because of import competition, experienced information technology workers whose jobs have been outsourced to workers in other countries, and mid-level managers in positions eliminated through corporate restructuring). It examines current policies targeted at the reemployment of older displaced workers which, if successful, might lengthen their stay in the workforce.
Date: January 15, 2010
Creator: Levine, Linda
Object Type: Report
System: The UNT Digital Library
Highlights of the 2009 SEG summer research workshop on"CO2 Sequestration Geophysics" (open access)

Highlights of the 2009 SEG summer research workshop on"CO2 Sequestration Geophysics"

The 2009 SEG Summer Research Workshop on CO2 Sequestration Geophysics was held August 23-27, 2009 in Banff, Canada. The event was attended by over 100 scientists from around the world, which proved to be a remarkably successful turnout in the midst of the current global financial crisis and severe corporate travel restrictions. Attendees included SEG President Larry Lines (U. Calgary), and CSEG President John Downton (CGG Veritas), who joined SRW Chairman David Lumley (UWA) in giving the opening welcome remarks at the Sunday Icebreaker. The workshop was organized by an expert technical committee (see side bar) representing a good mix of industry, academic, and government research organizations. The format consisted of four days of technical sessions with over 60 talks and posters, plus an optional pre-workshop field trip to the Columbia Ice Fields to view firsthand the effects of global warming on the Athabasca glacier (Figures 1-2). Group technical discussion was encouraged by requiring each presenter to limit themselves to 15 minutes of presentation followed by a 15 minute open discussion period. Technical contributions focused on the current and future role of geophysics in CO2 sequestration, highlighting new research and field-test results with regard to site selection and characterization, monitoring …
Date: January 15, 2010
Creator: Lumley, D.; Sherlock, D.; Daley, T.; Huang, L.; Lawton, D.; Masters, R. et al.
Object Type: Article
System: The UNT Digital Library
Liquid Metal Walls, Lithium, And Low Recycling Boundary Conditions In Tokamaks (open access)

Liquid Metal Walls, Lithium, And Low Recycling Boundary Conditions In Tokamaks

At present, the only solid material believed to be a viable option for plasma-facing components (PFCs) in a fusion reactor is tungsten. Operated at the lower temperatures typical of present-day fusion experiments, tungsten is known to suffer from surface degradation during long-term exposure to helium-containing plasmas, leading to reduced thermal conduction to the bulk, and enhanced erosion. Existing alloys are also quite brittle at temperatures under 700oC. However, at a sufficiently high operating temperature (700 - 1000 oC), tungsten is selfannealing and it is expected that surface damage will be reduced to the point where tungsten PFCs will have an acceptable lifetime in a reactor environment. The existence of only one potentially viable option for solid PFCs, though, constitutes one of the most significant restrictions on design space for DEMO and follow-on fusion reactors. In contrast, there are several candidates for liquid metal-based PFCs, including gallium, tin, lithium, and tin-lithium eutectics. We will discuss options for liquid metal walls in tokamaks, looking at both high and low recycling materials. We will then focus in particular on one of the candidate liquids, lithium. Lithium is known to have a high chemical affinity for hydrogen, and has been shown in test stands1 …
Date: January 15, 2010
Creator: Majeski, R.
Object Type: Article
System: The UNT Digital Library
Haiti Earthquake: Crisis and Response (open access)

Haiti Earthquake: Crisis and Response

This report discusses the Haiti earthquake disaster and various responses, ranging from the Haitian government's initial response to foreign humanitarian and financial aid.
Date: January 15, 2010
Creator: Margesson, Rhoda & Taft-Morales, Maureen
Object Type: Report
System: The UNT Digital Library
Spectral induced polarization signatures of abiotic FeS precipitation (open access)

Spectral induced polarization signatures of abiotic FeS precipitation

In recent years, geophysical methods have been shown to be sensitive to microbial induced mineralization processes. The spectral induced polarization (SIP) method appears to be very promising for monitoring mineralization and microbial processes. With this work, we study the links of mineralization and SIP signals, in the absence of microbial activity. We recorded the SIP response during abiotic FeS precipitation. We show that the SIP signals are diagnostic of FeS mineralization and can be differentiated from SIP signals from bio-mineralization processes. More specifically the imaginary conductivity shows almost linear dependence on the amount of FeS precipitating out of solution, above the threshold value 0.006 gr under our experimental conditions. This research has direct implications for the use of the SIP method as a monitoring, and decision making, tool for sustainable remediation of metals in contaminated soils and groundwater.
Date: January 15, 2010
Creator: Ntarlagiannis, D.; Doherty, R. & Williams, K. H.
Object Type: Article
System: The UNT Digital Library