Double band inversion in 
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-Sn: Appearance of topological surface states and the role of orbital composition

Rogalev, V. A.; Rauch, Tomáš; Scholz, Markus; Reis, Felix; Dudy, L.; Fleszar, A.; Husanu, Marius-Adrian; Strocov, Vladimir N.; Henk, Jürgen; Mertig, Ingrid; Schäfer, J.; Claessen, R.

doi:10.1103/physrevb.95.161117

Cited by 33 publications

(47 citation statements)

References 53 publications

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“…Our results hold also for diamond and zinc-blende semiconductors with a non-trivial fundamental band gap, such as strained α-Sn and HgTe [21], for which a another TSS was recently revealed in the valence band in addition to the established TSS at the Fermi level [22].…”

Section: Introductionsupporting

confidence: 79%

“…Due to possible strong hybridization of a TSS with bulk states (as predicted by theory) we prefer excitations by soft X-rays rather than by low-energy (vacuumultraviolet) photons, as the former provide increased bulk sensitivity and k ⊥ resolution [40]. Recall that previous SX-ARPES measurements resolved a TSS in the SO-gap of α-Sn [22]. Figure 4 presents SX-ARPES data measured on (001)terminated surfaces of InSb and GaAs.…”

Section: Experimental Aspectsmentioning

confidence: 89%

“…This SO-gap extends throughout the entire BZ, which allows to characterize the topological properties of the bands below the LH and HH pair. For α-Sn [22] and Hg x Cd 1−x Te [28] it has been shown that the LH and the HH bands as well as those below the SO-gap are topologically non-trivial. Here we show that also semiconductors with a trivial fundamental band gap can host a topologically non-trivial SO-gap.…”

Section: Theoretical Aspectsmentioning

confidence: 99%

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Nontrivial topological valence bands of common diamond and zinc-blende semiconductors

Rauch

Rogalev

Bauernfeind

et al. 2019

Phys. Rev. Materials

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The diamond and zinc-blende semiconductors are well-known and have been widely studied for decades. Yet, their electronic structure still surprises with unexpected topological properties of the valence bands. In this joint theoretical and experimental investigation we demonstrate for the benchmark compounds InSb and GaAs that the electronic structure features topological surface states below the Fermi energy. Our parity analysis shows that the spin-orbit split-off band near the valence band maximum exhibits a strong topologically non-trivial behavior characterized by the Z2 invariants (1; 000). The non-trivial character emerges instantaneously with non-zero spin-orbit coupling, in contrast to the conventional topological phase transition mechanism. Ab initio-based tight-binding calculations resolve topological surface states in the occupied electronic structure of InSb and GaAs, further confirmed experimentally by soft X-ray angle-resolved photoemission from both materials. Our findings are valid for all other materials whose valence bands are adiabatically linked to those of InSb, i.e., many diamond and zinc-blende semiconductors, as well as other related materials, such as half-Heusler compounds. arXiv:1904.05063v1 [cond-mat.mtrl-sci]

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Section: Introductionsupporting

confidence: 79%

Section: Experimental Aspectsmentioning

confidence: 89%

Section: Theoretical Aspectsmentioning

confidence: 99%

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Nontrivial topological valence bands of common diamond and zinc-blende semiconductors

Rauch

Rogalev

Bauernfeind

et al. 2019

Phys. Rev. Materials

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“…Even in two-dimensional graphene on SiC, the lifetime of ∼5 fs 60 is comparable to α-Sn. In a recent study, we were able to show that the TSS we investigated is derived mainly from p z -orbitals, while the Γ + 8 band, the projection of which is degenerate with the TSS, has mainly p x + p y character 6 . One may, therefore, argue about 'orbital protection' against interband scattering for the TSS in α-Sn.…”

Section: Many-body Interactionsmentioning

confidence: 82%

“…2(b)], which closes along the direction perpendicular to the (001) surface, i.e., along the Γ-Z direction [ Fig. 2(a)] 5,6 . This gives rise to two three-dimensional Dirac points along the line Z-Γ-Z and defines α-Sn as a topological Dirac semimetal.…”

Section: Electronic Structurementioning

confidence: 98%

Topological surface state of α−Sn on InSb(001) as studied by photoemission

et al. 2018

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We report on the electronic structure of the elemental topological semimetal α-Sn on InSb(001). High-resolution angle-resolved photoemission data allow to observe the topological surface state (TSS) that is degenerate with the bulk band structure and show that the former is unaffected by different surface reconstructions. An unintentional p-type doping of the as-grown films was compensated by deposition of potassium or tellurium after the growth, thereby shifting the Dirac point of the surface state below the Fermi level. We show that, while having the potential to break time-reversal symmetry, iron impurities with a coverage of up to 0.25 monolayers do not have any further impact on the surface state beyond that of K or Te. Furthermore, we have measured the spin-momentum locking of electrons from the TSS by means of spin-resolved photoemission. Our results show that the spin vector lies fully in-plane, but it also has a finite radial component. Finally, we analyze the decay of photoholes introduced in the photoemission process, and by this gain insight into the many-body interactions in the system. Surprisingly, we extract quasiparticle lifetimes comparable to other topological materials where the TSS is located within a bulk band gap. We argue that the main decay of photoholes is caused by intraband scattering, while scattering into bulk states is suppressed due to different orbital symmetries of bulk and surface states.

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Thermal Stability Enhancement in Epitaxial Alpha Tin Films by Strain Engineering

et al. 2019

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Exploring new topological materials with large topological nontrivial bandgaps and simple composition is attractive for both theoretical investigation and experimental realization. Recently, alpha tin (α-Sn) has been predicted to be such a candidate, and it can be tuned to be either a topological insulator or a Dirac semimetal by applying appropriate strain. However, freestanding α-Sn is only stable below 13.2 C. Herein, a series of high-quality α-Sn films with different thicknesses are successfully grown on InSb substrates by molecular beam epitaxy (MBE). Confirmed by both X-ray diffraction (XRD) and reciprocal space mapping (RSM), all the films remain fully strained up to 400 nm, proving the strain effect from the substrate. Remarkably, the single-crystalline α phase can persist up to 170 C for the 20 nm thick sample. The critical temperature where the α phase disappears decreases as the film thickness increases, showing that the thermal stabilization can be engineered by varying the α-Sn thickness. A plastic flow model considering work hardening is introduced to explain this dependence, assuming that the strain relaxation and the phase transition occur successively. This enhanced thermal stability is prerequisite for aforementioned roomtemperature characterization and practical application of this material system.The diamond-structured allotrope of tin (alpha tin [α-Sn]), also known as gray tin, has attracted increasing research interest recently for its topological characters when the cubic symmetry is broken. [1][2][3][4][5][6] The advantages of this material are attributed to its simple structure and large tunable nontrivial bandgap. [2][3][4][5][6][7][8][9][10][11][12]

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Double band inversion in α -Sn: Appearance of topological surface states and the role of orbital composition

Cited by 33 publications

References 53 publications

Nontrivial topological valence bands of common diamond and zinc-blende semiconductors

Nontrivial topological valence bands of common diamond and zinc-blende semiconductors

Topological surface state of α−Sn on InSb(001) as studied by photoemission

Thermal Stability Enhancement in Epitaxial Alpha Tin Films by Strain Engineering

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