Ab-initio modelling of strongly-correlated systems: Surprises and Perspectives
Markus Aichhorn
Institut für Theoretische Physik - Computational Physics
09:15 - 10:00 Thursday 23 October 2014 Rechbauerstrasse 12, HSII Strongly-correlated materials show a variety of fascinating
properties, such as metal-insulator transitions, unconventional
superconductivity, or magnetism, that cannot be explained by standard
band-theory of solids. A common feature of these fascinating materials
is that potential and kinetic energy are of similar strength, compete
with each other, yielding fragile and easy-to-perturbe ground states.
Until a few years ago, it was commonly accepted that strong
correlations occur only in systems with transition metals with open 3d
shells shifted. Only recently it was realized that in particular
Hunds rule coupling plays an important role in many materials,
resulting in highly unexpected behavior also in compounds built from
4d transition metal elements. For instance, we will see how unprecedented
strong magnetism in technetium oxides can be traced back to the Hunds rule
coupling.
Strong correlations do also appear in materials with 5d elements, such as
iridium oxides. Only the combination of strong spin orbit coupling and
electronic correlations can turn this system into an insulating state,
which is in agreement with experimental data.
I will also give some perspectives on future developments,
and the quest for predictive power, in the field of ab-initio computer
simulations for correlated materials.
|
