11,959 research outputs found
Mott physics in electron dioxygenyl magnet : OF (=Sb, Pt)
We have investigated electronic structures and magnetic properties of
OF (=Sb, Pt), which are composed of two building blocks of
strongly correlated electrons: O dioxygenyls and F
octahedra, by employing the first-principles electronic structure band method.
For OSbF, as a reference system of OPtF, we have shown
that the Coulomb correlation of O(2) electrons drives the Mott insulating
state. For OPtF, we have demonstrated that the Mott insulating
state is induced by the combined effects of the Coulomb correlation of O(2)
and Pt(5) electrons and the spin-orbit (SO) interaction of Pt(5) states.
The role of the SO interaction in forming the Mott insulating state of
OPtF is similar to the case of SrIrO that is a
prototype of a SO induced Mott system with J.Comment: 5 pages, 6 figure
The Finite- Impurity Anderson Model in the presence of an external magnetic field
We have investigated effects of an external magnetic field in the impurity
Anderson model with a finite on-site Coulomb repulsion . Large
expansion is employed in the slave boson representation, by taking into account
, , and subspaces. To evaluate the vertex function for the
``empty state boson" self-energy, we have devised two approximations which
reduce much computational efforts without losing general features of the model.
It is found that the Kondo temperature is reduced by the presence of a magnetic
field, and that at low field and at low temperature, the field dependence of
both the Kondo temperature and the impurity magnetization exhibits a scaling
behavior with high accuracy. Further, some interesting features are found in
the field dependence of the impurity magnetization at finite temperature, the
physical implications of which are discussed in terms of the renormalized Kondo
temperature.Comment: 18 pages Revtex, 7 Postscript figures, To appear in Phys.Rev.
Effects of the Spin-Orbit Coupling and the Superconductivity in simple-cubic alpha-Polonium
We have investigated the mechanism of stabilizing the simple-cubic (SC)
structure in polonium (alpha- Po), based on the phonon dispersion calculations
using the first-principles all-electron band method. We have demonstrated that
the stable SC structure results from the suppression of the Peierls instability
due to the strong spin-orbit coupling (SOC) in alpha-Po. Further, we have
explored the possible superconductivity in alpha-Po, and predicted that it
becomes a superconductor with Tc ~ 4 K. The transverse soft phonon mode at q ~
2/3 R, which is greatly influenced by the SOC, plays an important role both in
the structural stability and the superconductivity in alpha-Po. We have
discussed effects of the SOC and the volume variation on the phonon dispersions
and superconducting properties of alpha-Po.Comment: 5pages, 5figure
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