SciPost Phys. 3, 041 (2017) ·
published 22 December 2017
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Semi-Dirac fermions are known to exist at the critical points of topological
phase transitions requiring fine-tuning of the parameters. We show that robust
semi-Dirac points can appear in a heterostructure consisting of superconducting
Sr2IrO4 and a t2g electron system (t2g-ES) without fine-tuning. They are
topologically stable in the presence of the symmetries of the model, metallic
t2g-ES and a single active band in Sr2IrO4. If the t2g metal is coupled to two
different layers of Sr2IrO4 (effectively a multiband superconductor) in a
three-layer-structure the semi-Dirac points can split into two stable Dirac
points with opposite chiralities. A similar transition can be achieved if the
t2g-ES supports intrinsic triplet superconductivity. By considering Sr2RuO4 as
an example of a t2g-ES we predict a rich topological phase diagram as a
function of various parameters.
