Ripple-modulated electronic structure of a 3D topological insulator

Okada, Yoshinori; Zhou, Wenwen; Walkup, Daniel; Dhital, Chetan; Wilson, Stephen D.; Madhavan, Vidya

doi:10.1038/ncomms2150

Cited by 31 publications

(34 citation statements)

References 37 publications

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“…A flat surface is shaped into a corrugation with parallel ridges and grooves. The height of the corrugation is in the range of tens of picometers, comparably small as that of other stain-induced corrugations [44][45][46] . Without an atomic resolution in this experiment, we cannot make a quantitative analysis of the strain based on precise determination of atomic displacement 34,46 .…”

Section: Resultsmentioning

confidence: 71%

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Possible strain induced Mott gap collapse in 1T-TaS2

Zhang

et al. 2019

Commun Phys

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Tuning the electronic properties of a matter is of fundamental interest in scientific research as well as in applications. Recently, the Mott insulator-metal transition has been reported in a pristine layered transition metal dichalcogenides 1T -TaS 2 , with the transition triggered by an optical excitation, a gate controlled intercalation, or a voltage pulse. However, the sudden insulatormetal transition hinders an exploration of how the transition evolves. Here, we report the strain as a possible new tuning parameter to induce Mott gap collapse in 1T -TaS 2 . In a strain-rich area, we find a mosaic state with distinct electronic density of states within different domains. In a corrugated surface, we further observe and analyze a smooth evolution from a Mott gap state to a metallic state. Our results shed new lights on the understanding of the insulator-metal transition and promote a controllable strain engineering on the design of switching devices in the future. * yiyin@zju.edu.cn 1 arXiv:2005.13311v2 [cond-mat.str-el] 28 May 2020

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Section: Resultsmentioning

confidence: 71%

“…4). The corrugation is also a possible strain-induced feature 43,44 . In this corrugated area, we observe a smooth evolution of Mott-gap collapse across the corrugation, which gives us a special example to analyze the Mott insulator-metal transition.…”

Section: Resultsmentioning

confidence: 99%

Possible strain induced Mott gap collapse in 1T-TaS2

Zhang

et al. 2019

Commun Phys

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“…In fact, LL spectroscopy and QPI imaging have shed light on several aspects of Dirac materials. For example, they have been used to visualize the absence and onset of backscattering in topological materials [39][40][41], pseudospin protection in graphene [38,42] and chemical potential fluctuations in a range of materials [17,42,43]. While each of these techniques offers great promise on its own for measuring simpler band structures, the synergistic utilization of LLs and QPI could also enable the determination of multi-component band structures.…”

Section: Quasiparticle Interferencementioning

confidence: 99%

Momentum-resolved STM studies of Rashba-split surface states on the topological semimetal Sb

Soumyanarayanan

Hoffman

2015

Journal of Electron Spectroscopy and Related Phenomena

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Topological materials host protected surface states with locked spin and momentum degrees of freedom. The helical Dirac character of the surface states, of tremendous scientific interest, stems from the interplay of the bulk band structure and surface Rashba spin-orbit interaction. The semimetal Sb offers a pristine platform to examine the Rashba origins of the Dirac-like topological surface states. Here we present an overview of our momentum-resolved scanning tunneling spectroscopy studies of Sb, over an extended (300 meV) energy range, revealing several features characteristic of the emergence of the Dirac-like surface states from a conventional Rashba-type parabolic dispersion. Our work provides a conceptual framework to create and investigate tunable Rashba states with topological properties.

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“…Having identified the important energy scales, we proceed to the application of the Fourier-transform quasiparticle interference (FT-QPI) on this system. FT-QPI imaging has been successfully applied to extract the band structure of many complex systems, such as high-temperature superconductors, [26][27][28] heavy-fermion compounds 29,30 and Z 2 topological materials [31][32][33] , but this technique is yet to be fully utilized for spin-and orbitaltexture mapping of extracted bands. Representative FTs of dI/dV conductance maps acquired over a 1300Å square region of Pb 0.70 Sn 0.30 Se are shown in Fig.…”

mentioning

confidence: 99%

Mapping the unconventional orbital texture in topological crystalline insulators

et al. 2014

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The newly discovered topological crystalline insulators feature a complex band structure involving multiple Dirac cones [1][2][3][4][5][6] , and are potentially highly tunable by external electric field, temperature or strain. Theoretically, it has been predicted that the various Dirac cones, which are o set in energy and momentum, might harbour vastly di erent orbital character 7 . However, their orbital texture, which is of immense importance in determining a variety of a material's properties [8][9][10] remains elusive. Here, we unveil the orbital texture of Pb 1−x Sn x Se, a prototypical topological crystalline insulator. By using Fourier-transform scanning tunnelling spectroscopy we measure the interference patterns produced by the scattering of surface-state electrons. We discover that the intensity and energy dependences of the Fourier transforms show distinct characteristics, which can be directly attributed to orbital e ects. Our experiments reveal a complex band topology involving two Lifshitz transitions 11 and establish the orbital nature of the Dirac bands, which could provide an alternative pathway towards future quantum applications.A counterpart to charge and spin, electron orbitals are of great importance in the underlying physical processes of a variety of systems. The orbital degrees of freedom, for example, play a crucial role in the colossal magnetoresistance effect in manganese oxides, and contribute to the anisotropic electronic and magnetic properties in many other transition-metal oxide systems 8 . More recently, orbital ordering within the superconducting FeAs layer has been thought to govern structural phase transitions and 'stripe'-like antiferromagnetism in Fe-based high-temperature superconductors 9,10 . Similarly, topological materials host complex orbital arrangements often strongly coupled to other electronic degrees of freedom [12][13][14][15][16][17][18] . Topological crystalline insulators (TCIs) in particular are predicted to exhibit intricate band, spin and orbital textures, potentially relevant for interactions in the quantum Hall regime. Although previous experiments provided a glimpse into the complex band topology present in TCIs (refs 3-5,19,20), these experimental efforts have not been able to shed light onto its orbital texture. Here we use Fourier-transform (FT) scanning tunnelling spectroscopy (STS) to reveal the distinct orbital nature of the Dirac bands in the TCI, Pb 1−x Sn x Se.In its stoichiometric state, Pb 1−x Sn x Se with x = 0 is a trivial insulator under the Z 2 topological classification of materials owing to the absence of band inversion. The process of adding Sn, which substitutes for Pb, leads to band inversion at an even number of time-reversal points, and the solutions remain Z 2 trivial. However, for a particular region of the composition-temperature parameter space, such as x > ∼0.23 and room temperature, or x > ∼0.18 and 4 K, topologically protected surface states emerge owing to the non-trivial band topology classified by crystalline symmetries 3...

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Ripple-modulated electronic structure of a 3D topological insulator

Cited by 31 publications

References 37 publications

Possible strain induced Mott gap collapse in 1T-TaS2

Possible strain induced Mott gap collapse in 1T-TaS2

Momentum-resolved STM studies of Rashba-split surface states on the topological semimetal Sb

Mapping the unconventional orbital texture in topological crystalline insulators

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