Inducing a Magnetic Monopole with Topological Surface States

Qi, Xiao-Liang; Li, Rundong; Zang, Jiadong; Zhang, Shou-Cheng

doi:10.1126/science.1167747

Cited by 946 publications

(926 citation statements)

References 19 publications

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“…Many intriguing phenomena such as weak anti‐localization, quantum spin, and anomalous Hall effect have been discovered in TIs 3, 4, 5, 6. The interplay between TIs and magnetism or superconductivity can even lead to the possible realization of magnetic monopoles7 or Majorana fermions 8. Therefore, the study of topological insulators has been one of the recent focuses of condensed matter physics and material science.…”

Section: Introductionmentioning

confidence: 99%

Magnetoresistance Anomaly in Topological Kondo Insulator SmB₆ Nanowires with Strong Surface Magnetism

Gan

et al. 2018

Advanced Science

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Topological Kondo insulators (TKIs) are a new class of topological materials in which topological surface states dominate the transport properties at low temperatures. They are also an ideal platform for studying the interplay between strong electron correlations and topological order. Here, hysteretic magnetoresistance (MR) is observed in TKI SmB6 thin nanowires at temperatures up to 8 K, revealing the strong magnetism at the surface of SmB6. It is also found that such MR anomaly exhibits an intriguing finite size effect and only appears in nanowires with diameter smaller than 58 nm. These nontrivial phenomena are discussed in terms of the latest Kondo breakdown model, which incorporates the RKKY magnetic interaction mediated by surface states with the strong electron correlation in SmB6. It would provide new insight into the nature of TKI surface states. Additionally, a non‐monotonically temperature dependent positive magnetoresistance is observed at intermediate temperatures, suggesting the possible impurity‐band conduction in SmB6, other than the surface state transport at low temperatures and the bulk‐band transport at high temperatures.

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Section: Introductionmentioning

confidence: 99%

Magnetoresistance Anomaly in Topological Kondo Insulator SmB₆ Nanowires with Strong Surface Magnetism

Gan

et al. 2018

Advanced Science

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“…The surface conductivity arises from the fact that strong spinorbit coupling renders the inversion between the bulk conduction and valence bands, thereby giving rise to spin-polarized topological surface states (TSSs) possessing a unique linear dispersion characteristic of massless particles [1][2][3][4][5][6][7][8][9][10] .…”

Section: Introductionmentioning

confidence: 99%

Rapid Surface Oxidation of Sb₂Te₃ as Indication for a Universal Trend in the Chemical Reactivity of Tetradymite Topological Insulators

et al. 2016

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Within the last few years topological insulators (TIs) have attracted a lot of interest due to their unique electronic structure with spin-polarized topological surface states (TSSs), which may pave the way for these materials to have a great potential in multiple applications. However, to enable consideration of TIs as building blocks for novel devices, stability of TSSs towards oxidation should be tested. Among the family of TIs with tetradymite structure, Sb 2 Te 3 is of p-type and appears to be the least explored material since its TSS is unoccupied in the ground state, a property that allows the use of optical excitations to generate spin currents relevant for spintronics. Here, we report relatively fast surface oxidation of Sb 2 Te 3 under ambient conditions. We show that the clean surface reacts rapidly with molecular oxygen and slowly with water, and that humidity plays an important role at the stage of the oxide-layer growth. In humid air, we show that Sb 2 Te 3 oxidizes in a time scale of minutes to hours, and much faster than other tetradymite TIs. The high surface reactivity revealed by our experiments is of critical importance and must be taken into account for the production and exploitation of novel TI-based devices using Sb 2 Te 3 as working material. Our results provide a fundamental and comprehensive understanding of the universal trend underlying the chemical reactivity of TIs.2

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“…1,2 The unique metallic states at the surface of a TI can be used both as a tabletop playground to prove fundamental concepts developed for particle physics and also as a new materials platform for intriguing quantum applications in both spin electronics and quantum computing. [3][4][5] The first three-dimensional TI to be experimentally realized was a Bi-Sb alloy, 6 following a theoretical prediction by Fu and Kane. 7 The topological nature of the alloy is inherited from the parent element antimony, which has a nontrivial principal topological invariant ν 0 , whereas bismuth has a trivial Z 2 invariant.…”

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confidence: 99%

Topological surface states scattering in antimony

2012

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In this work we study the topologically protected states of the Sb(111) surface by using ab initio transport theory. In the presence of a strong surface perturbation we obtain standing-wave states resulting from the superposition of spin-polarized surface states. By Fourier analysis, we identify the underlying two dimensional scattering processes and the spin texture. We find evidence of resonant transmission across surface barriers at quantum well state energies and evaluate their lifetimes. Our results are in excellent agreement with experimental findings. We also show that despite the presence of a step edge along a different high-symmetry direction, the surface states exhibit unperturbed transmission around the Fermi energy for states with near to normal incidence. Introduction. In the past few years topological insulators (TIs) have become an intensely studied field of condensed matter physics. 1,2 The unique metallic states at the surface of a TI can be used both as a tabletop playground to prove fundamental concepts developed for particle physics and also as a new materials platform for intriguing quantum applications in both spin electronics and quantum computing. [3][4][5] The first three-dimensional TI to be experimentally realized was a Bi-Sb alloy, 6 following a theoretical prediction by Fu and Kane. 7 The topological nature of the alloy is inherited from the parent element antimony, which has a nontrivial principal topological invariant ν 0 , whereas bismuth has a trivial Z 2 invariant. 8 Although Sb itself is a semimetal, its (111) surface hosts two spin-polarized bands, which extend around the Fermi energy E F . These form a single distorted Dirac cone where the lower bands are lifted upwards. The electronic properties of Sb(111) thin films have been investigated both theoretically and experimentally. [9][10][11][12] In a recent experiment, Seo et al. demonstrated that the topological surface states are extraordinarily insensitive to the presence of surface barriers. 13 They probed the extended nature of Sb(111) surface states by using a scanning tunneling microscope (STM) and found that these transmit across surface atomic steps with a high probability. Their analysis of the standing-wave states on surface terraces revealed the novel chiral spin texture of the two surface states, consistent with earlier angle-resolved photoemission spectroscopy (ARPES) measurements. 14 In this Rapid Communication we seek to theoretically recreate the above-mentioned experiment by using ab initio transport theory, and show that we can reproduce the formation of quantum well states and their lifetimes, as well as the wavelengths and phase shifts of the scattering states. Thereby we demonstrate that by first-principles calculations one can describe the correct scattering properties of such topologically protected surface states. In addition to comparing our results favorably to the experiments, we predict the scattering properties of these states in the presence of a surface perturbation along a direction orthogonal...

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Inducing a Magnetic Monopole with Topological Surface States

Cited by 946 publications

References 19 publications

Magnetoresistance Anomaly in Topological Kondo Insulator SmB₆ Nanowires with Strong Surface Magnetism

Magnetoresistance Anomaly in Topological Kondo Insulator SmB₆ Nanowires with Strong Surface Magnetism

Rapid Surface Oxidation of Sb₂Te₃ as Indication for a Universal Trend in the Chemical Reactivity of Tetradymite Topological Insulators

Topological surface states scattering in antimony

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Inducing a Magnetic Monopole with Topological Surface States

Cited by 946 publications

References 19 publications

Magnetoresistance Anomaly in Topological Kondo Insulator SmB6 Nanowires with Strong Surface Magnetism

Magnetoresistance Anomaly in Topological Kondo Insulator SmB6 Nanowires with Strong Surface Magnetism

Rapid Surface Oxidation of Sb2Te3 as Indication for a Universal Trend in the Chemical Reactivity of Tetradymite Topological Insulators

Topological surface states scattering in antimony

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Resources

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Magnetoresistance Anomaly in Topological Kondo Insulator SmB₆ Nanowires with Strong Surface Magnetism

Magnetoresistance Anomaly in Topological Kondo Insulator SmB₆ Nanowires with Strong Surface Magnetism

Rapid Surface Oxidation of Sb₂Te₃ as Indication for a Universal Trend in the Chemical Reactivity of Tetradymite Topological Insulators