Quantum well structure of a double perovskite superlattice and formation of a spin-polarized two-dimensional electron gas

Abstract

Layered oxide heterostructures are the new routes to tailor desired electronic and magnetic phases emerging from competing interactions involving strong correlation, orbital hopping, tunnelling and lattice coupling phenomena. Here, we propose a half-metal/insulator superlattice that intrinsically forms spin-polarized two-dimensional electron gas (2DEG) following a mechanism very different from the widely reported 2DEG at the single perovskite polar interfaces. From DFT$+U$ study on Sr${}_2$FeMoO${}_6$/La${}_2$CoMnO${}_6$ (001) superlattice, we find that a periodic quantum well is created along [001] which breaks the three-fold $t_{2g}$ degeneracy to separate the doubly degenerate $xz$ and $yz$ states from the planar $xy$ state. In the spin-down channel, the dual effect of quantum confinement and strong correlation localizes the degenerate states, whereas the dispersive $xy$ state forms the 2DEG which is robust against perturbations to the superlattice symmetry. The spin-up channel retains the bulk insulating. Both spin polarization and orbital polarization make the superlattice ideal for spintronic and orbitronic applications. The suggested 2DEG mechanism widens the scope of fabricating next generation of oxide heterostructures.

10 pages, 12 figures

References in corpus (6)

• Quantum ESPRESSO: a modular and open-source software project for quantum simulations of materials
• BoltzTraP. A code for calculating band-structure dependent quantities
• Emergent properties hidden in plane view: Strong electronic correlations at oxide interfaces
• Quantized conductance doubling and hard gap in a two-dimensional semiconductor-superconductor heterostructure
• Universality in the Electronic Structure of 3d Transition Metal Oxides
• Electronic structure of half-metallic magnets

Cited by in corpus (3)

• Defect-induced modulation of magnetic, electronic and optical properties of double perovskite oxide La${}_2$CoMnO${}_6$
• Facet Dependent Catalytic Activities of Anatase TiO${}_2$ for CO${}_2$ Adsorption and Conversion
• Quantum Confinement Induced Metal-Insulator Transition in Strongly Correlated Quantum Wells of SrVO${}_3$ Superlattice