Temperature-Induced Coexistence of a Conducting Bilayer and the Bulk-Terminated Surface of the Topological Insulator Bi<sub>2</sub>Te<sub>3</sub>

Coelho, Paula Mariel; Ribeiro, Guilherme A. S.; Malachias, A.; Pimentel, V. L.; Silva, Wendell S.; Reis, Diogo Duarte dos; Mazzoni, Mário S. C.; Magalhães-Paniago, R.

doi:10.1021/nl402450b

Cited by 33 publications

(41 citation statements)

References 21 publications

(31 reference statements)

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“…Furthermore, elastic relaxation due to the stress mismatch between BiTe monolayer and Bi 2 Te 3 surface forms a Mosaic pattern in the BiTe monolayer. In contrast to the previous studies about the surface stability, which are mainly surface decomposition or reaction [18,19], this work presents a long term effect induced by the bulk intercalated atoms. Since intercalation of atoms commonly exist in vdW gaps [20,21], it is expected that such a novel mechanism may exist in other layered materials as well, considering the intrinsic nature of vdW interactions.…”

Section: Pacs Numbersmentioning

confidence: 74%

mentioning

confidence: 74%

“…A low-energy ion scattering (LEIS) study confirmed a way of surface degradation of Bi 2 Se 3 , i.e., the cleaved surface in UHV undergoes a fast Se evaporation and is thus terminated by Bi bilayer [18]. It was also observed that annealing induces the surface segregation of Bi bilayer [19]. Therefore, a direct characterization of surface evolution upon long term exposure in UHV is important, which, however, hasn't been reported yet.…”

Section: Pacs Numbersmentioning

confidence: 91%

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Aggregation of BiTe monolayer on Bi2Te3 (111) induced by diffusion of intercalated atoms in the van der Waals gap

Wang¹,

Huang²,

Zhang³

et al. 2017

Phys. Rev. B

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We report a post-growth aging mechanism of Bi2Te3(111) films with scanning tunneling microscopy in combination with density functional theory calculation. It is found that a monolayered structure with a squared lattice symmetry gradually aggregates from surface steps. Theoretical calculations indicate that the van der Waals (vdW) gap not only acts as a natural reservoir for selfintercalated Bi and Te atoms, but also provides them easy diffusion pathways. Once hopping out of the gap, these defective atoms prefer to develop into a two dimensional BiTe superstructure on the Bi2Te3(111) surface driven by positive energy gain. Considering the common nature of weakly bonding between vdW layers, we expect such unusual diffusion and aggregation of the intercalated atoms may be of general importance for most kinds of vdW layered materials. PACS numbers:Studies on bismuth chalcogenide (Bi 2 X 3 ) have long been focused regarding the potential in thermoelectricity [1], and also been revived recently by the discovery of topological insulators (TIs) [2][3][4][5][6][7][8][9][10]. It has been confirmed that most Bi 2 X 3 compounds, such as Bi 2 Te 3 , Bi 2 Se 3 and Sb 2 Se 3 , are prototypical 3D TIs [5][6][7][8]. Hosting the topological surface states and gapped bulk band structure, Bi 2 X 3 becomes promising in the future applications such as quantum computation and spintronic etc [2][3][4].In spite of the robustness of the topological surface states against time-reversal invariant perturbation, temporal stability of the surface or interface still greatly affects the Bi 2 X 3 's performance and application. Intensive studies have been conducted regarding the surface atomistic and band structure evolution upon exposing to various gases including air [11][12][13][14][15][16][17], however it still remains elusive whether and how the Bi 2 X 3 intrinsically evolves in ultrahigh vacuum (UHV). ARPES studies indicated that a long stay in UHV induces an energy band splitting [11]. A low-energy ion scattering (LEIS) study confirmed a way of surface degradation of Bi 2 Se 3 , i.e., the cleaved surface in UHV undergoes a fast Se evaporation and is thus terminated by Bi bilayer [18]. It was also observed that annealing induces the surface segregation of Bi bilayer [19]. Therefore, a direct characterization of surface evolution upon long term exposure in UHV is important, which, however, hasn't been reported yet.In this Letter, we demonstrate a post-growth aggregation on Bi 2 Te 3 (111) surface induced by the selfintercalation and diffusion of Bi and Te atoms in the van der Waals (vdW) gap with scanning tunneling microscopy (STM) in combination with density functional theory (DFT) calculation. We observe that upon long term aging, a monolayered Mosaic pattern, presumably composed of Bi and Te, is gradually formed starting at the step edges of Bi 2 Te 3 (111) surface. DFT calculations confirm that Bi atoms prefer to be intercalated in the vdW gap between quintuple layers (QLs) than being adsorbed on the surface, and the difference between ...

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Section: Pacs Numbersmentioning

confidence: 74%

mentioning

confidence: 74%

Section: Pacs Numbersmentioning

confidence: 91%

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Aggregation of BiTe monolayer on Bi2Te3 (111) induced by diffusion of intercalated atoms in the van der Waals gap

Wang¹,

Huang²,

Zhang³

et al. 2017

Phys. Rev. B

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“…Th: Si 2014 Bi Th: Murakami 2006, Wada 2011Exp: Jnawali 2012, Hirayama 2011, Hirahara 2012, Wells 2009, Lükermann 2012, Coelho 2013, Chun-Lei 2013, Lu 2015, Takayama 2015Sb Th: Zhang 2012Exp: Yao 2013, Bian 2011 BiTeX (X=I, Br, Cl) Th: HgTe/CdTe Th: Bernevig 2006, Khaymovich 2013Exp: König 2007, Brüne 2012, Nowack 2013, Zholudev 2012, Gusev 2014, Hart 2014 * In the interest of brevity, only the last name of the first author is given. However, in cases of multiple references with the same name and year, titles of the articles should allow the reader to access the appropriate literature.…”

Section: Graphenementioning

confidence: 99%

Colloquium: Topological band theory

2016

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The first-principles band theory paradigm has been a key player not only in the process of discovering new classes of topologically interesting materials, but also for identifying salient characteristics of topological states, enabling direct and sharpened confrontation between theory and experiment. We begin this review by discussing underpinnings of the topological band theory, which basically involves a layer of analysis and interpretation for assessing topological properties of band structures beyond the standard band theory construct. Methods for evaluating topological invariants are delineated, including crystals without inversion symmetry and interacting systems. The extent to which theoretically predicted properties and protections of topological states have been verified experimentally is discussed, including work on topological crystalline insulators, disorder/interaction driven topological insulators (TIs), topological superconductors, Weyl semimetal phases, and topological phase transitions. Successful strategies for new materials discovery process are outlined. A comprehensive survey of currently predicted 2D and 3D topological materials is provided. This includes binary, ternary and quaternary compounds, transition metal and f-electron materials, Weyl and 3D Dirac semimetals, complex oxides, organometallics, skutterudites and antiperovskites. Also included is the emerging area of 2D atomically thin films beyond graphene of various elements and their alloys, functional thin films, multilayer systems, and ultra-thin films of 3D TIs, all of which hold exciting promise of wide-ranging applications. We conclude by giving a perspective on research directions where further work will broadly benefit the topological materials field.

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“…Note that a sample with metallic Bi at the surface is labeled here as Bi-rich, instead of Bi-terminated, as it's not always clear if the excess Bi forms an epitaxial overlayer, amorphous film or isolated metallic islands. Coelho, et al demonstrated the coexistence of a Bi bilayer termination and a Te-termination on a Bi 2 Te 3 surface prepared by ion bombardment and annealing (IBA) [16]. Bi 2 Te 3 has the same crystal structure as Bi 2 Se 3 and is also a TI.…”

Section: Introductionmentioning

confidence: 99%

Termination of single-crystal Bi2Se3 surfaces prepared by various methods

2016

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Bismuth Selenide (Bi 2 Se 3 ) is a topological insulator with a two-dimensional layered structure that enables clean and well-ordered surfaces to be prepared by cleaving. Although some studies have demonstrated that the cleaved surface is terminated with Se, as expected from the bulk crystal structure, other reports have indicated either a Bi-or mixed-termination. Low energy ion scattering (LEIS), low energy electron diffraction (LEED) and x-ray photoelectron spectroscopy (XPS) are used here to compare surfaces prepared by ex situ cleaving, in situ cleaving, and ion bombardment and annealing (IBA) in ultra-high vacuum (UHV). Surfaces prepared by in situ cleaving and IBA are well ordered and Se-terminated. Ex situ cleaved samples could be either Se-terminated or Bi-rich, are less well ordered and have adsorbed contaminants. This suggests that a chemical reaction involving atmospheric contaminants, which may preferentially adsorb at surface defects, could contribute to the non-reproducibility of the termination. ____________

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Temperature-Induced Coexistence of a Conducting Bilayer and the Bulk-Terminated Surface of the Topological Insulator Bi₂Te₃

Cited by 33 publications

References 21 publications

Aggregation of BiTe monolayer on Bi2Te3 (111) induced by diffusion of intercalated atoms in the van der Waals gap

Aggregation of BiTe monolayer on Bi2Te3 (111) induced by diffusion of intercalated atoms in the van der Waals gap

Colloquium: Topological band theory

Termination of single-crystal Bi2Se3 surfaces prepared by various methods

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Temperature-Induced Coexistence of a Conducting Bilayer and the Bulk-Terminated Surface of the Topological Insulator Bi2Te3

Cited by 33 publications

References 21 publications

Aggregation of BiTe monolayer on Bi2Te3 (111) induced by diffusion of intercalated atoms in the van der Waals gap

Aggregation of BiTe monolayer on Bi2Te3 (111) induced by diffusion of intercalated atoms in the van der Waals gap

Colloquium: Topological band theory

Termination of single-crystal Bi2Se3 surfaces prepared by various methods

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Temperature-Induced Coexistence of a Conducting Bilayer and the Bulk-Terminated Surface of the Topological Insulator Bi₂Te₃