19,913 research outputs found
STM imaging of electronic waves on the surface of BiTe: topologically protected surface states and hexagonal warping effects
Scanning tunneling spectroscopy studies on high-quality BiTe crystals
exhibit perfect correspondence to ARPES data, hence enabling identification of
different regimes measured in the local density of states (LDOS). Oscillations
of LDOS near a step are analyzed. Within the main part of the surface band
oscillations are strongly damped, supporting the hypothesis of topological
protection. At higher energies, as the surface band becomes concave,
oscillations appear which disperse with a particular wave-vector that may
result from an unconventional hexagonal warping term.Comment: 4 pages, 4 figures. Revised manuscript with improved analysis and
figure
Direct Optical Coupling to an Unoccupied Dirac Surface State in the Topological Insulator BiSe
We characterize the occupied and unoccupied electronic structure of the
topological insulator BiSe by one-photon and two-photon angle-resolved
photoemission spectroscopy and slab band structure calculations. We reveal a
second, unoccupied Dirac surface state with similar electronic structure and
physical origin to the well-known topological surface state. This state is
energetically located 1.5 eV above the conduction band, which permits it to be
directly excited by the output of a Ti:Sapphire laser. This discovery
demonstrates the feasibility of direct ultrafast optical coupling to a
topologically protected, spin-textured surface state.Comment: Accepted to Physical Review Letter
Yohannan\u27s Revolution in World Missions: One Man\u27s Mission to Change a Generation (Book Review)
The Impact of the Christian Faith on Library Service
The library profession is in flux and uncertainty due to its lack of a well-founded philosophy of service. The Christian faith provides the necessary philosophical framework. Three implications follow from the application of a Christian worldview to library practice. First, Christian librarians should provide access to collections that will allow students to integrate faith and learning. Second, they should demonstrate love and concern for library users by offering diligent, humble service.Third, they should teach students the ethical use of information resources. Christianity has an impact on “library service” in three areas. First, the word library presumes a collection of library materials: books, periodicals, microfilms, motion pictures, cassettes, records, and other forms of media. Second, the word service signifies the way the librarian goes about helping people find answers to their information needs.Third, correct use of library resources connotes proper library ethics. Before this paper discusses these three areas, it will be useful to survey the current state of library philosophy
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