  The type-II Dirac fermions that are characterized by a tilted Dirac cone and
anisotropic magneto-transport properties have been recently proposed
theoretically and confirmed experimentally. Here, we predict the emergence of
two-dimensional type-II Dirac fermions in LaAlO3/LaNiO3/LaAlO3 quantum-well
structures. Using first-principles calculations and model analysis, we show
that the Dirac points are formed at the crossing between the dx2-y2 and dz2
bands protected by the mirror symmetry. The energy position of the Dirac points
can be tuned to appear at the Fermi energy by changing the quantum-well width.
For the quantum-well structure with a two-unit cell thick LaNiO3 layer, we
predict the coexistence of the type-II Dirac points and the Dirac nodal line.
The results are analyzed and interpreted using a tight-binding model and
symmetry arguments. Our findings offer a practical way to realize the 2D
type-II Dirac fermions in oxide heterostructures.
