Evidence for a positron bound state on the surface of a topological insulator

Shastry, K.; Weiss, A. H.; Barbiellini, B.; Assaf, Badih A.; Lim, Zheng Hui; Joglekar, Prasad; Heiman, D.

doi:10.1088/1742-6596/618/1/012006

Cited by 2 publications

(5 citation statements)

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“…The linear fit shown in figure 2(c), yields E T h = 1.8 eV. Next, by considering the measured activation energy E a = 0.4 eV for positronium (Ps) desorption from the surface 4 , one can eliminate the electron workfunction using the expression 9 , E a = E b + φ − − 6.80 eV, which gives a binding energy of E b = 2.7±0.2 eV (ref. 4).…”

Section: Resultsmentioning

confidence: 99%

“…The technical details concerning the setup of the positron experiments can be found in ref. 4 and references therein. Positrons annihilate predominantly with the valence electrons but the small fraction that annihilates with core electrons produces highly unstable core holes, which are filled by the Auger process.…”

Section: Resultsmentioning

confidence: 99%

“…A schematic picture of the process is drawn in figure 1(a). Results of PAES experiments from the TI Bi 2 Te 2 Se surface are shown in figure 1(b), where signals from Bi, Te, Se, C and O can be identified; the latter two are caused by the presence of a small concentration of contaminants adsorbed on the surface 4 . These results reveal the presence of a bound positron SS.…”

Section: Resultsmentioning

confidence: 99%

“…We can theoretically determine the activation energy for Ps desorption from a Bi 2 Te 2 Se, of which the experimental results are described in ref. 4, by calculating the particle's binding energy to the surface. In order to model the Ps state, we consider the Schrödinger equation for a neutral particle in an effective potential well 29 .…”

Section: Positronium Modelmentioning

confidence: 99%

“…Our calculations show that spin-polarized positron beams can additionally resolve the spin-textures associated with the topological states, owing to the predominant annihilation between particles with opposite spins 3 . In section II, we present the experimental evidence for the existence of a bound positron state at the surface of the TI Bi 2 Te 2 Se and the measured binding energy 4 . Section III contains a discussion of the theory and computational details used in our first principles investigations.…”

Section: Introductionmentioning

confidence: 99%

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Positron surface state as a spectroscopic probe for characterizing surfaces of topological insulator materials

et al. 2016

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Topological insulators are attracting considerable interest due to their potential for technological applications and as platforms for exploring wide-ranging fundamental science questions. In order to exploit, fine-tune, control and manipulate the topological surface states, spectroscopic tools which can effectively probe their properties are of key importance. Here, we demonstrate that positrons provide a sensitive probe for topological states, and that the associated annihilation spectrum provides a new technique for characterizing these states. Firm experimental evidence for the existence of a positron surface state near Bi2Te2Se with a binding energy of E b = 2.7 ± 0.2 eV is presented, and is confirmed by first-principles calculations. Additionally, the simulations predict a significant signal originating from annihilation with the topological surface states and shows the feasibility to detect their spin-texture through the use of spin-polarized positron beams.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Positronium Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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