Metallic Interface Emerging at Magnetic Domain Wall of Antiferromagnetic Insulator---Fate of Extinct Weyl Electrons

TL;DR

This paper theoretically demonstrates the emergence of a two-dimensional metallic interface at magnetic domain walls in antiferromagnetic insulators, revealing novel topological states and magnetic control mechanisms that could impact spintronics.

Contribution

It introduces a new type of metallic interface at magnetic domain walls in antiferromagnetic insulators, linked to topological zero modes and protected by weak Chern insulator invariants.

Findings

Emergent 2D metallic states at magnetic domain walls.

Protection of these states by topological invariants.

Potential for magnetic control of electronic transport.

Abstract

Topological insulators, in contrast to ordinary semiconductors, accompany protected metallic surfaces described by Dirac-type fermions. Here, we theoretically show another emergent two-dimensional metal embedded in the bulk insulator is realized at a magnetic domain wall. The domain wall has long been studied as ingredients of both old-fashioned and leading-edge spintronics. The domain wall here, as an interface of seemingly trivial antiferromagnetic insulators, emergently realizes a functional interface preserved by zero modes with robust two-dimensional Fermi surfaces, where pyrochlore iridium oxides proposed to host condensed-matter realization of Weyl fermions offer such examples at low temperatures. The existence of ingap states pinned at domain walls, theoretically resembling spin/charge solitons in polyacetylene, and protected as the edge of hidden one-dimensional weak Chern insulators characterized by a zero-dimensional class A topological invariant, solves experimental puzzles observed in R2Ir2O7 with rare earth elements R. The domain wall realizes a novel quantum confinement of electrons and embosses a net uniform magnetization, which enables magnetic control of electronic interface transports beyond semiconductor paradigm.