Magnetically tuned topological phase in graphene nanoribbon heterojunctions

Abstract

The interplay between topology and magnetism often triggers the exotic quantum phases. Here, we report an accessible scheme to engineer the robust ${\mathbb{Z}}_2$ topology by intrinsic magnetism, originating from the zigzag segment connecting two armchair segments with different width, in one-dimensional graphene nanoribbon heterojunctions. Our first-principle and model simulations reveal that the emergent spin polarization substantially modifies the dimerization between junction states, forming the special SSH mechanism depending on the magnetic configurations. Interestingly, the topological phase in magnetic state is only determined by the width of the narrow armchair segment, in sharp contrast with that in the normal state. In addition, the emergent magnetism increases the bulk energy band gap by an order of magnitude than that in the nonmagnetic state. We also discuss the $\mathbb{Z}$ topology of the junction states and the termination-dependent of topological end states. Our results bring new way to tune the topology in graphene nanoribbon heterostructure, providing a new platform for future one-dimensional topological devices and molecular-scale spintronics.

5 pages, 5 figures

References in corpus (21)

• Quantum ESPRESSO: a modular and open-source software project for quantum simulations of materials
• Quantum Spin Hall Insulator State in HgTe Quantum Wells
• Energy Gaps in Graphene Nanoribbons
• Superconducting proximity effect and Majorana fermions at the surface of a topological insulator
• Topological Insulators with Inversion Symmetry
• Topological Field Theory of Time-Reversal Invariant Insulators
• Topological Crystalline Insulators
• Room temperature magnetic order on zigzag edges of narrow graphene nanoribbons
• Colloquium: Quantum anomalous Hall effect
• Magnetism in Disordered Graphene and Irradiated Graphite
• Graphene nanoribbons for quantum electronics
• Ab initio GW many-body effects in graphene
• Bulk-boundary correspondence from the inter-cellular Zak phase
• Competition between spin and charge polarized states in nanographene ribbons with zigzag edges
• Topological phase transition in chiral graphene nanoribbons: from edge bands to end states
• Probing the magnetism of topological end-states in 5-armchair graphene nanoribbons
• Second Order Topological Insulator State in Hexagonal Lattices and its Abundant Material Candidates
• Electric Field Tunable Topological Phases in Graphene Nanoribbons
• Correlated Topological States in Graphene Nanoribbon Heterostructures
• Width-tuned magnetic order oscillation on zigzag edges of honeycomb nanoribbons
• Second-order topological insulator in Bilayer borophene