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Search Results: 1 - 10 of 433080 matches for " J. D. Denlinger "
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Generalized Spectral Signatures of Electron Fractionalization in Quasi-One and -Two Dimensional Molybdenum Bronzes and Superconducting Cuprates
G. -H. Gweon,J. W. Allen,J. D. Denlinger
Physics , 2003, DOI: 10.1103/PhysRevB.68.195117
Abstract: We establish the quasi-one-dimensional Li purple bronze as a photoemission paradigm of Luttinger liquid behavior. We also show that generalized signatures of electron fractionalization are present in the angle resolved photoemission spectra for quasi-two-dimensional purple bronzes and certain cuprates. An important component of our analysis for the quasi-two-dimensional systems is the proposal of a ``melted holon'' scenario for the k-independent background that accompanies but does not interact with the peaks that disperse to define the Fermi surface.
Bulk Band Gaps in Divalent Hexaborides: A Soft X-Ray Emission Study
J. D. Denlinger,G. -H. Gweon,J. W. Allen,A. D. Bianchi,Z. Fisk
Physics , 2001,
Abstract: Boron K-edge soft x-ray emission and absorption are used to address the fundamental question of whether divalent hexaborides are intrinsic semimetals or defect-doped bandgap insulators. These bulk sensitive measurements, complementary and consistent with surface-sensitive angle-resolved photoemission experiments, confirm the existence of a bulk band gap and the location of the chemical potential at the bottom of the conduction band.
Temperature Dependent 5f-states in URu_2Si_2
J. D. Denlinger,G. -H. Gweon,J. W. Allen,J. L. Sarrao
Physics , 2001, DOI: 10.1016/S0921-4526(01)01290-X
Abstract: A dramatic temperature dependent enhancement of U 5f spectral weight at $E_F$ is observed in angle-resolved photoemission measurements of $URu_2Si_2$ at the center of an X-point hole-pocket. Comparison of this temperature dependent behavior for excitation both at and below the U $5d \to 5f$ resonant threshold is presented.
Photoemission view of electron fractionalization in quasi-one dimensional metal Li$_{0.9}$Mo$_6$O$_{17}$
G. -H. Gweon,J. D. Denlinger,C. G. Olson,H. H?chst,J. Marcus,C. Schlenker
Physics , 2001, DOI: 10.1016/S0921-4526(01)01284-4
Abstract: We report Luttinger liquid line shapes better revealed by new angle resolved photoemission data taken with a much improved angle resolution on a quasi-1-dimensional metal Li$_{0.9}$Mo$_6$O$_{17}$. The new data indicate a larger spinon velocity than our previous lower resolution data indicated.
Observation of a $d$-wave gap in electron-doped Sr$_2$IrO$_4$
Y. K. Kim,N. H. Sung,J. D. Denlinger,B. J. Kim
Physics , 2015, DOI: 10.1038/nphys3503
Abstract: High temperature superconductivity in cuprates emerges out of a highly enigmatic `pseudogap' metal phase. The mechanism of high temperature superconductivity is likely encrypted in the elusive relationship between the two phases, which spectroscopically is manifested as Fermi arcs---disconnected segments of zero-energy states---collapsing into $d$-wave point nodes upon entering the superconducting phase. Here, we reproduce this distinct cuprate phenomenology in the 5$d$ transition-metal oxide Sr$_2$IrO$_4$. Using angle-resolved photoemission, we show that clean, low-temperature phase of 6-8$\%$ electron-doped Sr$_2$IrO$_4$ has gapless excitations only at four isolated points in the Brillouin zone with a predominant $d$-wave symmetry of the gap. Our work thus establishes a connection between the low-temperature $d$-wave instability and the previously reported high-temperature Fermi arcs in electron-doped Sr$_2$IrO$_4$. Although the physical origin of the $d$-wave gap remains to be understood, Sr$_2$IrO$_4$ is a first non-cuprate material to spectroscopically reproduce the complete phenomenology of the cuprates, thus off?ering a new material platform to investigate the relationship between the pseudogap and the $d$-wave gap.
Yb Valence Change in (Ce,Yb)CoIn5 from spectroscopy and bulk properties
L. Dudy,J. D. Denlinger,L. Shu,M. Janoschek,J. W. Allen,M. B. Maple
Physics , 2013, DOI: 10.1103/PhysRevB.88.165118
Abstract: The electronic structure of (Ce,Yb)CoIn5 has been studied by a combination of photoemission, x-ray absorption and bulk property measurements. Previous findings of a Ce valence near 3+ for all x and of an Yb valence near 2.3+ for x>0.3 were confirmed. One new result of this study is that the Yb valence for x<0.2 increases rapidly with decreasing x from 2.3+ toward 3+, which correlates well with de Haas van Alphen results showing a change of Fermi surface around x=0.2. Another new result is the direct observation by angle resolved photoemission Fermi surface maps of about 50% cross sectional area reductions of the \alpha- and \beta-sheets for x=1 compared to x=0, and a smaller, essentially proportionate, size change of the \alpha-sheet for x=0.2. These changes are found to be in good general agreement with expectations from simple electron counting. The implications of these results for the unusual robustness of superconductivity and Kondo coherence with increasing x in this alloy system are discussed.
Gene discovery using massively parallel pyrosequencing to develop ESTs for the flesh fly Sarcophaga crassipalpis
Daniel A Hahn, Gregory J Ragland, D Shoemaker, David L Denlinger
BMC Genomics , 2009, DOI: 10.1186/1471-2164-10-234
Abstract: We obtained 207,110 ESTs with an average read length of 241 bp. These reads assembled into 20,995 contigs and 31,056 singletons. Using BLAST searches of the NR and NT databases we were able to identify 11,757 unique gene elements (E<0.0001) representing approximately 9,000 independent transcripts. Comparison of the distribution of S. crassipalpis unigenes among GO Biological Process functional groups with that of the Drosophila melanogaster transcriptome suggests that our ESTs are broadly representative of the flesh fly transcriptome. Insertion and deletion errors in 454 sequencing present a serious hurdle to comparative transcriptome analysis. Aided by a new approach to correcting for these errors, we performed a comparative analysis of genetic divergence across GO categories among S. crassipalpis, D. melanogaster, and Anopheles gambiae. The results suggest that non-synonymous substitutions occur at similar rates across categories, although genes related to response to stimuli may evolve slightly faster. In addition, we identified over 500 potential microsatellite loci and more than 12,000 SNPs among our ESTs.Our data provides the first large-scale EST-project for flesh flies, a much-needed resource for exploring this model species. In addition, we identified a large number of potential microsatellite and SNP markers that could be used in population and systematic studies of S. crassipalpis and other flesh flies.Flesh flies in the genus Sarcophaga (Diptera: Sarcophagidae) have long been important models in insect physiology and biochemistry, particularly with respect to the study of endocrinology [1,2], diapause [3,4], cold hardiness [5,6], reproduction [7,8], and immunity [9]. Larvae of Sarcophaga flies typically feed on carrion or feces, playing an important ecological role in decomposition and feature prominently in human forensic studies [10,11]. Sarcophaga species can cause myiasis in humans and livestock and therefore are of importance to medical and veterina
Photoemission Spectroscopy and the Unusually Robust One Dimensional Physics of Lithium Purple Bronze
L. Dudy,J. D. Denlinger,J. W. Allen,F. Wang,J. He,D. Hitchcock,A. Sekiyama,S. Suga
Physics , 2012, DOI: 10.1088/0953-8984/25/1/014007
Abstract: Temperature dependent photoemission spectroscopy in Li0.9Mo6O17 contributes to evidence for one dimensional physics that is unusually robust. Three generic characteristics of the Luttinger liquid are observed, power law behavior of the k-integrated spectral function down to temperatures just above the superconducting transition, k-resolved lineshapes that show holon and spinon features, and quantum critical (QC) scaling in the lineshapes. Departures of the lineshapes and the scaling from expectations in the Tomonaga Luttinger model can be partially described by a phenomenological momentum broadening that is presented and discussed. The possibility that some form of 1d physics obtains even down to the superconducting transition temperature is assessed.
Soft x-ray spectroscopy experiments on the near K-edge of B in MB2 (M=Mg, Al, Ta, and Nb)
J. Nakamura,N. Yamada,K. Kuroki,T. A. Callcott,D. L. Ederer,J. D. Denlinger,R. C. C. Perera
Physics , 2001, DOI: 10.1103/PhysRevB.64.174504
Abstract: Soft X-ray absorption and emission measurements are performed for the K- edge of B in MB$_2$ (M=Mg, Al, Ta and Nb). Unique feature of MgB$_2$ with a high density of B 2$p_{xy}(\sigma)$-state below and above the Fermi edge, which extends to 1 eV above the edge, is confirmed. In contrast, the B 2$p$ density of states in AlB$_2$ and TaB$_2$, both of occupied and unoccupied states, decreased linearly towards the Fermi energy and showed a dip at the Fermi energy. Furthermore, there is a broadening of the peaks with $p\sigma$-character in XES and XAS of AlB$_2$, which is due to the increase of three dimensionality in the $p\sigma$-band in AlB$_2$. The DOS of NbB$_2$ has a dip just below the Fermi energy. The present results indicate that the large DOS of B-2$p\sigma$ states near the Fermi energy are crucial for the superconductivity of MgB$_2$.
Non-fermi-liquid single particle lineshape of the quasi-one-dimensional non-CDW metal Li_{0.9}Mo_{6}O_{17} : comparison to the Luttinger liquid
J. D. Denlinger,G. -H. Gweon,J. W. Allen,C. G. Olson,J. Marcus,C. Schlenker,L. -S. Hsu
Physics , 1999, DOI: 10.1103/PhysRevLett.82.2540
Abstract: We report the detailed non-Fermi liquid (NFL) lineshape of the dispersing excitation which defines the Fermi surface (FS) for quasi-one-dimensional Li_{0.9}Mo_{6}O_{17}. The properties of Li_{0.9}Mo_{6}O_{17} strongly suggest that the NFL behavior has a purely electronic origin. Relative to the theoretical Luttinger liquid lineshape, we identify significant similarities, but also important differences.
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