534 research outputs found
Field-induced Orbital Patterns in Ferromagnetic Layered Ruthenates
We study the evolution of orbital patterns in ferromagnetic layered
ruthenates due to the competition of Coulomb interactions, compressive c axis
and orthorhombic distortions in the presence of a polarizing orbital field
coupled to the angular momentum. By means of the exact diagonalization on a 2x2
cluster and a cluster embedded analysis where inter-plaquette interaction is
treated on mean field level, we determine the ground-state phase diagram.
Specifically, we demonstrate that, via the activation of two or three of t_2g
local orbital configurations, an external field applied along different
symmetry directions can lead to inequivalent orbital correlated states.
Starting from an antiferro-orbital pattern, for the easy axis case an orbital
ordered phase is induced, having strong next nearest neighbors ferro-orbital
correlations. Otherwise, a field applied along the hard axis leads a reduction
of local orbital moment in a way to suppress the orbital order.Comment: 11 page
Two-Fermi-surface superconducting state and a nodal d-wave gap in the electron-doped Sm(1.85)Ce(0.15)CuO(4-d) cuprate superconductor
We report on laser-excited angle-resolved photoemission spectroscopy (ARPES)
in the electron-doped cuprate Sm(1.85)Ce(0.15)CuO(4-d). The data show the
existence of a nodal hole-pocket Fermi-surface both in the normal and
superconducting states. We prove that its origin is long-range
antiferromagnetism by an analysis of the coherence factors in the main and
folded bands. This coexistence of long-range antiferromagnetism and
superconductivity implies that electron-doped cuprates are two-Fermi-surface
superconductors. The measured superconducting gap in the nodal hole-pocket is
compatible with a d-wave symmetry.Comment: 4 pages, 3 figures, accepted to Phys. Rev. Let
Benchmarking theoretical formalisms for ( p , p n ) reactions: The 15 C ( p , p n ) 14 C case
Background: Proton-induced knockout reactions of the form
(
p
,
p
N
)
have experienced a renewed interest in recent years due to the possibility of performing these measurements with rare isotopes, using inverse kinematics. Several theoretical models are being used for the interpretation of these new data, such as the distorted-wave impulse approximation (DWIA), the transition amplitude formulation of the Faddeev equations due to Alt, Grassberger, and Sandhas (FAGS) and, more recently, a coupled-channels method here referred to as transfer-to-the- continuum (TC).
Purpose: Our goal is to compare the momentum distributions calculated with the DWIA and TC models for the same reactions, using whenever possible the same inputs (e.g., distorting potential). A comparison with already published results for the FAGS formalism is performed as well.
Method: We choose the
15
C
(
p
,
p
n
)
14
C
reaction at an incident energy of 420 MeV/u, which has been previously studied with the FAGS formalism. The knocked-out neutron is assumed to be in a
2
s
single-particle orbital. Longitudinal and transverse momentum distributions are calculated for different assumed separation energies.
Results: For all cases considered, we find a very good agreement between DWIA and TC results. The energy dependence of the distorting optical potentials is found to affect in a modest way the shape and magnitude of the momentum distributions. Moreover, when relativistic kinematics corrections are omitted, our calculations reproduce remarkably well the FAGS result.
Conclusions: The results found in this work provide confidence on the consistency and accuracy of the DWIA and TC models for analyzing momentum distributions for
(
p
,
p
n
)
reactions at intermediate energies.Ministerio de Economía y Competitividad de España. FIS2014- 53448-C2-1-PPrograma de investigación e innovación Horizonte 2020 de la Unión Europea. 65400
Consistent anomalies of the induced W gravities
The BRST anomaly which may be present in the induced gravity quantized
on the light-cone is evaluated in the geometrical framework of Zucchini. The
cocycles linked by the cohomology of the BRST operator to the anomaly are
straightforwardly calculated thanks to the analogy between this formulation and
the Yang-Mills theory. We give also a conformally covariant formulation of
these quantities including the anomaly, which is valid on arbitrary Riemann
surfaces. The example of the theory is discussed and a comparison with
other candidates for the anomaly available in the literature is presented.Comment: Latex, no figures, 12 pages (To appear on Physics Letters B.
Tephra-stratigraphical study of the 1988-1989 eruption of Tokachi-dake Volcano, central Hokkaido
Twenty-three small-scale eruptions took place at Tokachi-dake from December 16, 1988 to March 5, 1989. The pyroclastic fall deposits, ballistic fragments, and pyroclastic surge and flow deposits were dispersed over the flank and leeward areas of the volcano. Because the pyroclasts of each eruption were well-preserved in snow during the winter, the stratigraphy and distribution of these deposits could be studied in detail. The volume of the pyroclastic fall deposits are nearly equal to those of the pyroclastic surge and flow deposits. The total volume of these pyroclasts is estimated to be 7.4×105 m3. Judging from the sequential changes of the volume and composition of the pyroclasts, the characteristic features of the eruption can be summarized as follows: At first, a vent was opened by ejection of altered rock fragments in December, 1988. Then, essential fragments were ejected in January, 1989. Finally the activity level of magma declined and the altered rock fragments content increased again in February to March, 1989
Analysis on photoemission spectrum of superconducting FeSe
In this paper, we present the result of soft X-ray photoemission spectroscopy and its comparison with the density functional calculation. Although local density approximation seems to be a good starting point for describing the electronic structure of FeSe, the simulated spectrum poorly reproduced the structure around E(B) = 2 eV. This result suggests the necessity of theoretical treatment beyond local density approximation
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