Two-dimensional type-II Dirac fermions in a LaAlO3/LaNiO3/LaAlO3 quantum well

Authors

L. L. Tao, University of Nebraska-LincolnFollow
Evgeny Y. Tsymbal, University of Nebraska-LincolnFollow

Date of this Version

9-4-2018

Citation

Physical Review B – Rapid Communications 98, 121102(R) (2018).
DOI: 10.1103/PhysRevB.98.121102

Comments

Copyright 2018 American Physical Society. Used by permission.

Abstract

The type-II Dirac fermions that are characterized by a tilted Dirac cone and anisotropic magnetotransport properties have been recently proposed theoretically and confirmed experimentally. Here, we predict the emergence of two-dimensional (2D) type-II Dirac fermions in LaAlO₃/LaNiO₃/LaAlO₃ quantum-well structures. Using first-principles calculations and model analyses, we show that the Dirac points are formed at the crossing between the d_x²−y² and d_z² 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 point and the closed nodal line. The results are analyzed and interpreted using a tight-binding model and symmetry arguments. Our findings offer a practical way to realize 2D type-II Dirac fermions in oxide heterostructures.