Signatures of Helical Edge Transport in Millimetre-Scale Thin Films of Na3Bi
arXiv:1906.01214 · doi:10.1021/acs.nanolett.0c01649
Abstract
A two-dimensional topological insulator (2DTI) has an insulating bulk and helical spin-polarised edge modes robust to backscattering by non-magnetic disorder. While ballistic transport has been demonstrated in 2DTIs over short distances, larger samples show significant backscattering and a nearly temperature-independent resistance whose origin is unclear. 2DTI edges have shown a spin polarisation, however the degree of helicity is difficult to quantify from spin measurements. Here, we study 2DTI few-layer Na3Bi on insulating Al2O3. A non-local conductance measurement geometry enables sensitive detection of the edge conductance in the topological regime, with an edge mean free path ~100 nm. Magnetic field suppresses spin-flip scattering in the helical edges, resulting in a giant negative magnetoresistance (GNMR), up to 80% at 0.9 T. Comparison to theory indicates >98% of scattering is helical spin scattering significantly exceeding the maximum (67%) expected for a non-helical metal. GNMR, coupled with non-local measurements demonstrating edge conduction, thus provides an unambiguous experimental signature of helical edges that we expect to be generically useful in understanding 2DTIs.
References in corpus (20)
- Quantum Spin Hall Insulator State in HgTe Quantum Wells
- Bismuthene on a SiC Substrate: A Candidate for a New High-Temperature Quantum Spin Hall Paradigm
- Nonlocal edge state transport in the quantum spin Hall state
- Realization of Quantum Spin Hall State in Monolayer 1T'-WTe2
- Observation of the Quantum Spin Hall Effect up to 100 Kelvin in a Monolayer Crystal
- Edge conduction in monolayer WTe2
- Giant negative magnetoresistance induced by the chiral anomaly in individual Cd3As2 nanowires
- Observation of Quantum Spin Hall States in InAs/GaSb Bilayers under Broken Time-Reversal Symmetry
- Gate-Tunable Negative Longitudinal Magnetoresistance in the Predicted Type-II Weyl Semimetal WTe2
- Imaging currents in HgTe quantum wells in the quantum spin Hall regime
- Kondo effect in the helical edge liquid of the quantum spin Hall state
- Electric Field-Tuned Topological Phase Transition in Ultra-Thin Na3Bi - Towards a Topological Transistor
- Images of edge current in InAs/GaSb quantum wells
- Room-temperature chiral charge pumping in Dirac semimetals
- Resistance of helical edges formed in a semiconductor heterostructure
- Persistence of two-dimensional topological insulator state in wide HgTe quantum well
- Neutral-current Hall effects in disordered graphene
- Nonlocal transport near the charge neutrality point in a two-dimensional electron-hole system
- Suppression of the Kondo Resistivity Minimum in Magnetic Topological Insulators
- Electrostatic Modulation of the Electronic Properties of Dirac Semimetal Na3Bi
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- The effect of magnetic impurity scattering on transport in topological insulators
- Spin-resolved spectroscopy of helical Andreev bound states
- Unidirectional magneto-transport of linearly dispersing topological edge states
- Extended Haldane model -- a modern gateway to topological insulators