764 research outputs found
Giant Intrinsic Spin and Orbital Hall Effects in Sr2MO4 (M=Ru,Rh,Mo)
We investigate the intrinsic spin Hall conductivity (SHC) and the d-orbital
Hall conductivity (OHC) in metallic d-electron systems, by focusing on the
t_{2g}-orbital tight-binding model for Sr2MO4 (M=Ru,Rh,Mo). The conductivities
obtained are one or two orders of magnitude larger than predicted values for
p-type semiconductors with 5% hole doping. The origin of these giant Hall
effects is the ``effective Aharonov-Bohm phase'' that is induced by the
d-atomic angular momentum in connection with the spin-orbit interaction and the
inter-orbital hopping integrals. The huge SHC and OHC generated by this
mechanism are expected to be ubiquitous in multiorbital transition metal
complexes, which pens the possibility of realizing spintronics as well as
orbitronics devices.Comment: 5 pages, accepted for publication in PR
Electromagnetic Response of a Superconductor: Effect of Order Parameter Collective Modes
Effects of order parameter collective modes on electromagnetic response are
studied for a clean spin-triplet superconductor with orbital
symmetry, which has been proposed as a candidate pairing symmetry for
SrRuO. It is shown that the superconductor has
characteristic massive collective modes analogous to the clapping mode in the
A-phase of superfluid He. We discuss the contribution from the collective
modes to ultrasound attenuation and electromagnetic absorption. We show that in
the electromagnetic absorption spectrum the clapping mode gives rise to a
resonance peak well below the pair breaking frequency, while the ultrasound
attenuation is hardly influenced by the collective excitations.Comment: 4 pages RevTex, 1 eps figur
Cellular Potts modeling of complex multicellular behaviors in tissue morphogenesis
Mathematical modeling is an essential approach for the understanding of complex multicellular behaviors in tissue morphogenesis. Here, we review the cellular Potts model (CPM; also known as the Glazier-Graner-Hogeweg model), an effective computational modeling framework. We discuss its usability for modeling complex developmental phenomena by examining four fundamental examples of tissue morphogenesis: (i) cell sorting, (ii) cyst formation, (iii) tube morphogenesis in kidney development, and (iv) blood vessel formation. The review provides an introduction for biologists for starting simulation analysis using the CPM framework
Spin Hall effect in Sr2RuO4 and transition metals (Nb,Ta)
We study the intrinsic spin Hall conductivity (SHC) and the -orbital Hall
conductivity (OHC) in metallic -electron systems based on the multiorbital
tight-binding model. The obtained Hall conductivities are much larger than that
in -type semiconductors. The origin of these huge Hall effects is the
"effective Aharonov-Bohm phase" induced by the signs of inter-orbital hopping
integrals as well as atomic spin-orbit interaction. Huge SHC and OHC due to
this mecahnism is ubiquitous in multiorbital transition metals.Comment: 4 pages, 3 figures, Proceedings of SNS conference in Sendai, 200
Giant Extrinsic Spin Hall Effect due to Rare-Earth Impurities
We investigate the extrinsic spin Hall effect in the electron gas model due
to magnetic impurities, by focusing on Ce- and Yb-impurities. In the dilute
limit, the skew scattering term dominates the side jump term. For
Ce-impurities, the spin Hall angle due to skew scattering is
given by , where is the phase shift
for partial wave. Since reaches if
\delta_2 \simge 0.03, the spin Hall effect is anticipated to be considerable
in metals with rare-earth impurities. The giant extrinsic SHE originates from
the large orbital angular momentum, which is also significant for the intrinsic
SHE.Comment: 5 pages, 3 figures, to be published in New Journal of Physic
Giant Orbital Hall Effect in Transition Metals: Origin of Large Spin and Anomalous Hall Effects
In transition metals and their compounds, the orbital degrees of freedom
gives rise to an orbital current, in addition to the ordinary spin and charge
currents. We reveal that considerably large spin and anomalous Hall effects
(SHE and AHE) observed in transition metals originate from an orbital Hall
effect (OHE). To elucidate the origin of these novel Hall effects, a simple
periodic s-d hybridization model is proposed as a generic model. The giant
positive OHE originates from the orbital Aharonov-Bohm phase factor, and
induces spin Hall conductivity that is proportional to the spin-orbit
polarization at the Fermi level, which is positive (negative) in metals with
more than (less than) half-filling.Comment: 5 pages, to be published in Phys. Rev. Let
Leading Temperature Corrections to Fermi Liquid Theory in Two Dimensions
We calculate the basic parameters of the Fermi Liquid: the scattering vertex,
the Landau interaction function, the effective mass, and physical
susceptibilities for a model of two-dimensional (2D) fermions with a short
ranged interaction at non-zero temperature. The leading temperature dependences
of the spin components of the scattering vertex, the Landau function, and the
spin susceptibility are found to be linear. T-linear terms in the effective
mass and in the ``charge-sector''- quantities are found to cancel to second
order in the interaction, but the cancellation is argued not to be generic. The
connection with previous studies of the 2D Fermi-Liquid parameters is
discussed.Comment: 4 pages, 1 figur
Phase Diagram of the Electron-Doped Cuprate Superconductors
We investigate the phase diagram of the electron-doped systems in high-Tc
cuprates. We calculate the superconducting transition temperature Tc, the
antiferromagnetic transition temperature TN, the NMR relaxation rate 1/T1 with
the antiferromagnetic fluctuations in the fluctuation-exchange (FLEX)
approximation and with the superconducting fluctuations in the self-consistent
t-matrix approximation. Obtained phase diagram has common features as those in
the hole-doped systems, including the antiferromagnetic state, the
superconducting state and the spin gap phenomenon. Doping-dependences of TN, Tc
and Tsg (spin gap temperature) are, however, different with those in the
hole-doped systems. These differences are due to the intrinsic nature of the
ingap states which are intimately related with the Zhang-Rice singlets in the
hole-doped systems and are correlated d-electrons in the electron-doped
systems, respectively, which has been shown in the d-p model.Comment: 4 pages, 3 figure
Reliability Investigation of Automatic Assessment of Learner-Build Concept Map with Kit-Build Method by Comparing with Manual Methods
This paper describes an investigation into the reliability of an automatic assessment method of the learner-build concept map by comparing it with two well-known manual methods. We have previously proposed the Kit-Build (KB) concept map framework where a learner builds a concept map by using only a provided set of components, known as the set "kit". In this framework, instant and automatic assessment of a learner-build concept map has been realized. We call this assessment method the "Kit-Build method" (KB method). The framework and assessment method have already been practically used in classrooms in various schools. As an investigation of the reliability of this method, we have conducted an experiment to compare the assessment results of the method with the assessment results of two other manual assessment methods. In this experiment, 22 university students attended as subjects and four as raters. It was found that the scores of the KB method had a very strong correlation with the scores of the other manual methods. The results suggest that automatic assessment of the Kit-Build concept map can attain almost the same level of reliability as well-known manual assessment methods.'Artificial Intelligence in Education' 18th International Conference, AIED 2017, Wuhan, China, June 28 – July 1, 2017, Proceeding
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