Orbital Magnetization of Quantum Spin Hall Insulator Nanoparticles

Abstract

Both spin and orbital degrees of freedom contribute to the magnetic moment of isolated atoms. However, when inserted in crystals, atomic orbital moments are quenched because of the lack of rotational symmetry that protects them when isolated. Thus, the dominant contribution to the magnetization of magnetic materials comes from electronic spin. Here we show that nanoislands of quantum spin Hall insulators can host robust orbital edge magnetism whenever their highest occupied Kramers doublet is singly occupied, upgrading the spin edge current into a charge current. The resulting orbital magnetization scales linearly with size, outweighing the spin contribution for islands of a few nm in size. This linear scaling is specific of the Dirac edge states and very different from Schrodinger electrons in quantum rings. Modelling Bi(111) flakes, whose edge states have been recently observed, we show that orbital magnetization is robust with respect to disorder, thermal agitation, shape of the island and crystallographic direction of the edges, reflecting its topological protection.

7 pages, 5 figures, + Supporting Information

References in corpus (6)

• Quantum Spin Hall Insulator State in HgTe Quantum Wells
• Quantum Spin Hall Effect and Enhanced Magnetic Response by Spin-Orbit Coupling
• Coupling of Spin and Orbital Motion of Electrons in Carbon Nanotubes
• Nanoscale magnetic imaging of a single electron spin under ambient conditions
• One-dimensional Topological Edge States of Bismuth Bilayers
• Topologically protected quantum transport in locally exfoliated bismuth at room temperature

Cited by in corpus (6)

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• Detection of graphene's divergent orbital diamagnetism at the Dirac point
• Topological phases in Bi/Sb planar and buckled honeycomb monolayers
• Stability of topological properties of bismuth (111) bilayer
• Low-energy electronic properties of Weyl semimetal quantum dot
• Entanglement entropy and entanglement spectrum of Bi${}_{1-x}$Sb${}_x$ (111) bilayers