SciPost Phys. 3, 041 (2017) ·
published 22 December 2017

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SemiDirac fermions are known to exist at the critical points of topological
phase transitions requiring finetuning of the parameters. We show that robust
semiDirac points can appear in a heterostructure consisting of superconducting
Sr2IrO4 and a t2g electron system (t2gES) without finetuning. They are
topologically stable in the presence of the symmetries of the model, metallic
t2gES 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
threelayerstructure the semiDirac points can split into two stable Dirac
points with opposite chiralities. A similar transition can be achieved if the
t2gES supports intrinsic triplet superconductivity. By considering Sr2RuO4 as
an example of a t2gES we predict a rich topological phase diagram as a
function of various parameters.