401 research outputs found
Structural precursor to adsorbate-induced reconstruction: C on Ni(100)
The local structure around adsorbed carbon atoms on Ni(100) has been determined at low coverage as well as in the 0.5 monolayer (2×2)p4g “clock” reconstruction by scanned energy mode photoelectron diffraction. At low coverage, there is no radial strain of the Ni atoms surrounding the adsorbed carbon, contrary to previous suggestions. None of the C-Ni near-neighbor distances are changed by reconstruction, but the Ni-Ni nearest-neighbor distance in the top layer increases significantly, showing that the adsorbate-induced compressive stress is associated with Ni-Ni, rather than Ni-C, repulsion
Multivariate models from RNA-Seq SNVs yield candidate molecular targets for biomarker discovery: SNV-DA
Breast: up and downstream SNVs model. (CSV 22.1 kb
Mn L3,2 X-ray Absorption Spectroscopy And Magnetic Circular Dichroism In Ferromagnetic (Ga,Mn)P
We have measured the X-ray absorption (XAS) and X-ray magnetic circular
dichroism (XMCD) at the Mn L3,2 edges in ferromagnetic Ga1-xMnxP films for
0.018<x<0.042. Large XMCD asymmetries at the L3 edge indicate significant
spin-polarization of the density of states at the Fermi energy. The spectral
shapes of the XAS and XMCD are nearly identical with those for Ga1-xMnxAs
indicating that the hybridization of Mn d states and anion p states is similar
in the two materials. Finally, compensation with sulfur donors not only lowers
the ferromagnetic Curie temperature but also reduces the spin polarization of
the hole states.Comment: 2 pages, 1 figure; To appear in the Proceedings of the 28th
International Conference on the Physics of Semiconductors (ICPS-28, Vienna,
Austria, July 24-28, 2006
Enhancement of the electronic contribution to the low temperature specific heat of Fe/Cr magnetic multilayer
We measured the low temperature specific heat of a sputtered
magnetic multilayer, as well as separate
thick Fe and Cr films. Magnetoresistance and magnetization
measurements on the multilayer demonstrated antiparallel coupling between the
Fe layers. Using microcalorimeters made in our group, we measured the specific
heat for and in magnetic fields up to for the multilayer. The
low temperature electronic specific heat coefficient of the multilayer in the
temperature range is . This is
significantly larger than that measured for the Fe or Cr films (5.4 and respectively). No magnetic field dependence of was
observed up to . These results can be explained by a softening of the
phonon modes observed in the same data and the presence of an Fe-Cr alloy phase
at the interfaces.Comment: 20 pages, 5 figure
Stable Weyl points, trivial surface states and particle-hole compensation in WP2
A possible connection between extremely large magneto-resistance and the
presence of Weyl points has garnered much attention in the study of topological
semimetals. Exploration of these concepts in transition metal phosphide WP2 has
been complicated by conflicting experimental reports. Here we combine
angle-resolved photoemission spectroscopy (ARPES) and density functional theory
(DFT) calculations to disentangle surface and bulk contributions to the ARPES
intensity, the superposition of which has plagued the determination of the
electronic structure in WP2. Our results show that while the hole- and
electron-like Fermi surface sheets originating from surface states have
different areas, the bulk-band structure of WP2 is electron-hole-compensated in
agreement with DFT. Furthermore, the detailed band structure is compatible with
the presence of at least 4 temperature-independent Weyl points, confirming the
topological nature of WP2 and its stability against lattice distortions.Comment: 6 pages, 4 figure
Surface states and Rashba-type spin polarization in antiferromagnetic MnBiTe
The layered van der Waals antiferromagnet MnBiTe has been predicted
to combine the band ordering of archetypical topological insulators such as
BiTe with the magnetism of Mn, making this material a viable candidate
for the realization of various magnetic topological states. We have
systematically investigated the surface electronic structure of
MnBiTe(0001) single crystals by use of spin- and angle-resolved
photoelectron spectroscopy experiments. In line with theoretical predictions,
the results reveal a surface state in the bulk band gap and they provide
evidence for the influence of exchange interaction and spin-orbit coupling on
the surface electronic structure.Comment: Revised versio
Theory of Excitonic States in CaB6
We study the excitonic states in CaB6 in terms of the Ginzburg-Landau theory.
By minimizing the free energy and by comparing with experimental results, we
identify two possible ground states with exciton condensation. They both break
time-reversal and inversion symmetries. This leads to various magnetic and
optical properties. As for magnetic properties, it is expected to be an
antiferromagnet, and its spin structure is predicted. It will exhibit the
magnetoelectric effect, and observed novel ferromagnetism in doped samples and
in thin-film and powder samples can arise from this effect. Interesting optical
phenomena such as the nonreciprocal optical effect and the second harmonic
generation are predicted. Their measurement for CaB6 will clarify whether
exciton condensation occurs or not and which of the two states is realized.Comment: 17 pages, 3 figure
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