58 research outputs found
Calculated Cleavage Behavior and Surface States of LaOFeAs
The layered structure of the iron based superconductors gives rise to a more
or less pronounced two-dimensionality of their electronic structure, most
pronounced in LaOFeAs. A consequence are distinct surface states to be expected
to influence any surface sensitive experimental probe. In this work a detailed
density functional analysis of the cleavage behavior and the surface electronic
structure of LaOFeAs is presented. The surface states are obtained to form
two-dimensional bands with their own Fermi surfaces markedly different from the
bulk electronic structure
Jahn-Teller like origin of the tetragonal distortion in disordered Fe-Pd magnetic shape memory alloys
The electronic structure and magnetic properties of disordered
FePd alloys are investigated in the framework
of density functional theory using the full potential local orbital method
(FPLO). Disorder is treated in the coherent potential approximation (CPA). Our
calculations explain the experimental magnetization data. The origin of the
tetragonal distortion in the Fe-Pd magnetic shape memory alloys is found to be
a Jahn-Teller like effect which allows the system to reduce its band energy in
a narrow composition range. Prospects for an optimization of the alloys'
properties by adding third elements are discussed
Emergence of quasi-one-dimensional physics in MoS(dmit), a nearly-isotropic three-dimensional molecular crystal
We report density functional theory calculations for MoS(dmit).
We derive an ab initio tight-binding model from overlaps of Wannier orbitals;
finding a layered model with interlayer hopping terms the size of the
in-plane terms. The in-plane Hamiltonian interpolates the kagom\'e and
honeycomb lattices. It supports states localized to dodecahedral rings within
the plane, which populate one-dimensional (1D) bands and lead to a quasi-1D
spin-one model on a layered honeycomb lattice once interactions are included.
Two lines of Dirac cones also cross the Fermi energy.Comment: 5 pages, 3 figure
SmO thin films: a flexible route to correlated flat bands with nontrivial topology
Using density functional theory based calculations, we show that the
correlated mixed-valent compound SmO is a 3D strongly topological semi-metal as
a result of a 4-5 band inversion at the X point. The [001] surface Bloch
spectral density reveals two weakly interacting Dirac cones that are
quasi-degenerate at the M_bar-point and another single Dirac cone at the
Gamma_bar-point. We also show that the topological non-triviality in SmO is
very robust and prevails for a wide range of lattice parameters, making it an
ideal candidate to investigate topological nontrivial correlated flat bands in
thin-film form. Moreover, the electron filling is tunable by strain. In
addition, we find conditions for which the inversion is of the 4f-6s type,
making SmO to be a rather unique system. The similarities of the crystal
symmetry and the lattice constant of SmO to the well studied ferromagnetic
semiconductor EuO, makes SmO/EuO thin film interfaces an excellent contender
towards realizing the quantum anomalous Hall effect in a strongly correlated
electron system.Comment: Paper+supplemen
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