New superconducting phase of Bi<sub>2</sub>Te<sub>3</sub>under pressure above 11 GPa

Einaga, Mari; Tanabe, Y; Nakayama, Atsuko; Ohmura, Ayako; Ishikawa, Fumihiro; Yamada, Yuh

doi:10.1088/1742-6596/215/1/012036

Cited by 55 publications

(60 citation statements)

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“…3) for X-ray data at 8.6 GP. This finding is consistent with that of previous report (21). Therefore, the superconductivity observed in our experiments has been verified to be coming from the parent structure of Bi 2 Te 3 , which preserves the topological property.…”

Section: Resultssupporting

confidence: 94%

“…1B). Such superconducting high-pressure phase (>6.3 GPa) has been reported previously (21); however, the different transition temperatures that are above 8 K in our measurement and around 2 K as reported in ref. 21 may originate from the different carrier types or densities of the samples as addressed in this paper.…”

Section: Resultssupporting

confidence: 76%

“…Such superconducting high-pressure phase (>6.3 GPa) has been reported previously (21); however, the different transition temperatures that are above 8 K in our measurement and around 2 K as reported in ref. 21 may originate from the different carrier types or densities of the samples as addressed in this paper. The major result of our paper is the discovery of the superconducting phase between 3.2-6.3 GPa, with the crystal structure being the same as in the ambient phase, in which the topological insulator behavior has been predicted and observed.…”

Section: Resultssupporting

confidence: 76%

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Pressure-induced superconductivity in topological parent compound Bi ₂ Te ₃

Zhang

Weng

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

299

166

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We report a successful observation of pressure-induced superconductivity in a topological compound Bi 2 Te 3 with T c of ∼3 K between 3 to 6 GPa. The combined high-pressure structure investigations with synchrotron radiation indicated that the superconductivity occurred at the ambient phase without crystal structure phase transition. The Hall effects measurements indicated the holetype carrier in the pressure-induced superconducting Bi 2 Te 3 single crystal. Consequently, the first-principles calculations based on the structural data obtained by the Rietveld refinement of X-ray diffraction patterns at high pressure showed that the electronic structure under pressure remained topologically nontrivial. The results suggested that topological superconductivity can be realized in Bi 2 Te 3 due to the proximity effect between superconducting bulk states and Dirac-type surface states. We also discuss the possibility that the bulk state could be a topological superconductor.high-pressure effects | pressure-tuned conductivity | topological superconductors U tilizing high pressure can be a very powerful method to generate new materials states, as demonstrated by either highpressure synthesis of new compounds, or pressure-tuned unique electronic states, such as insulator metal transitions. High pressure is particularly effective in tuning superconductivity as it is well documented that the record high superconducting transition temperature T c for either elements (1) or compounds (2) is created with the application of pressure. Recently, topological insulators (TIs) have generated great interest in the area of condensed matter physics (3-8). These materials have an insulating gap in the bulk, while also possessing conducting gapless edges or surface states in the boundaries that are protected by the timereversal symmetry (8, 9). Similar to TIs, topological superconductors have a full pairing gap in the bulk and gapless Majorana states on the edge or surface (10-13, 18). Majorana Fermions (14), half of ordinary Dirac fermions, could be very useful in topological quantum computing (15-17), which is proscriptive for new concept information technology.

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Section: Resultssupporting

confidence: 94%

Section: Resultssupporting

confidence: 76%

Section: Resultssupporting

confidence: 76%

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Pressure-induced superconductivity in topological parent compound Bi ₂ Te ₃

Zhang

Weng

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

299

166

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“…Searching for topological superconductivity is one of the hottest topics due to the exploration of fundamental physics and the potential applications in topological quantum computation [3,4]. Superconductivity has been found in some topological insulators such as compressed A 2 B 3 compounds including Bi 2 Te 3 [5][6][7][8][9], Bi 2 Se 3 [10,11], Sb 2 Te 3 [12], and Sb 2 Se 3 [13] and substituted Cu x Bi 2 Se 3 [14] together with related materials such as YPtBi [15]. However, the identification of their topological superconductivity is still a hard task and under debate [7,9].…”

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confidence: 99%

Realization of insulating state and superconductivity in the Rashba semiconductor BiTeCl

et al. 2016

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Layered non-centrosymmetric bismuth tellurohalides are being examined as candidates for topological insulators. Pressure is believed to be essential for inducing and tuning topological order in these systems. Through electrical transport and Raman scattering measurements, we find superconductivity in two high-pressure phases of BiTeCl with the different normal state features, carrier characteristics, and upper critical field behaviors. Superconductivity emerges when the resistivity maximum or charge density wave is suppressed by the applied pressure and then persists till the highest pressure of 51 GPa measured. The huge enhancement of the resistivity with three magnitude of orders indicates the possible achievement of the topological order in the dense insulating phase. These findings not only enrich the superconducting family from topological insulators but also pave the road on the search of topological superconductivity in bismuth tellurohalides.PACS numbers: 74.62. Fj, 74.25.Dw, Topological insulators represent the newly discovered phase of matter with insulating bulk state but topologically protected metallic surface state due to the timereversal symmetry and strong spin-orbital interaction [1,2]. Searching for topological superconductivity is one of the hottest topics due to the exploration of fundamental physics and the potential applications in topological quantum computation [3,4] [15]. However, the identification of their topological superconductivity is still a hard task and under debate [7,9]. In most cases, pressure is needed to drive topological insulators to superconductors. Superconductivity is usually accompanied by the electronic topological transition and/or structural transition [6,11]. It remains unclear whether such a transition is essential for inducing superconductivity in topological insulators.The class of non-centrosymmetric bismuth tellurohalides (BiTeX with X=Cl, Br, I) exhibit large Rashbatype splittings in the bulk bands [16][17][18][19][20], and they are potential candidates for building the spintronic devices. Pressure-induced topological quantum phase transition was predicted for Rashba semiconductor BiTeI [21]. However, controversial conclusions were drawn from the following experiments on this material [22,23]. Recently, BiTeCl was discovered to be the first example of inversion asymmetric topological insulator (IATI) from angleresolved photoemission spectroscopy (ARPES) experiment [24]. This was soon supported by the transport measurement [25]. Unlike the previously discovered three dimensional topological insulators with inversion symmetry, the inversion symmetry is naturally broken by the crystal structure in IATI. It is highly possible to realize the topological magneto-electric effects and the topological superconductivity [24,26,27]. However, quantum oscillation measurements excluded the existence of Dirac surface state in BiTeCl single crystals [28,29]. Such contradiction may come from the strong surface polarity which would generate large effective pressure along the ...

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“…When a conventional s-wave SC is brought near this metallic surface, a single MZM is trapped in the vortex core [7]. Since then, several TIs were found to exhibit bulk superconductivity on doping [8] or under pressure [9,10]. The normal phase of these SCs is now metallic, which raises the question: can a SC vortex host a surface MZM even when the bulk is not insulating?…”

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confidence: 99%

Majorana fermions inch closer to reality

Hughes¹

2011

Physics

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Recent experiments have observed bulk superconductivity in doped topological insulators. Here we ask whether vortex Majorana zero modes, previously predicted to occur when s-wave superconductivity is induced on the surface of topological insulators, survive in these doped systems with metallic normal states. Assuming inversion symmetry, we find that they do but only below a critical doping. The critical doping is tied to a topological phase transition of the vortex line, at which it supports gapless excitations along its length. The critical point depends only on the vortex orientation and a suitably defined SU (2) Majorana fermions, defined as fermions that are their own antiparticles unlike conventional Dirac fermions such as electrons, have long been sought by high energy physicists, but so far in vain. Of late, the search for Majorana fermions has remarkably shifted to condensed matter systems [1-3], especially, to superconductors (SCs), where states appear in conjugate pairs with equal and opposite energies. Then, a single state at zero energy is its own conjugate and hence, a Majorana state or a Majorana zero mode (MZM). These states are immune to local noise and hence, considered strong candidates for storing quantum information and performing fault tolerant quantum computation [4]. Moreover, they show non-Abelian rather than Bose or Fermi statistics which leads to a number of extraordinary phenomenon [5].Despite many proposals direct experimental evidence for a MZM is still lacking. While initial proposals involved the ¼ 5=2 quantum Hall state and SCs with unconventional pairing such as p x þ ip y [3], a recent breakthrough occurred with the discovery of topological insulators (TIs) [6], which feature topologically protected metallic surface bands. When a conventional s-wave SC is brought near this metallic surface, a single MZM is trapped in the vortex core [7]. Since then, several TIs were found to exhibit bulk superconductivity on doping [8] or under pressure [9,10]. The normal phase of these SCs is now metallic, which raises the question: can a SC vortex host a surface MZM even when the bulk is not insulating?In this Letter, we answer this question in the affirmative and in the process, discover a convenient way to obtain a MZM, which allows us to conclude that some existing experimental systems should possess these states. Our proposal involves simply passing a magnetic field through a TI-based SC, such as superconducting Bi 2 Te 3 , in which the doping is below a certain threshold value. We also find general criteria for SCs to host vortex MZMs and show that some non-TI-based SCs satisfy them too.A heuristic rule often applied to answer the above question is to examine whether the normal state bulk Fermi surface (FS) is well separated from surface states in the Brillouin zone. If it is, MZMs are assumed to persist in the bulk SC. While this may indicate the presence of low energy states, it is not a topological criterion since it depends on nonuniversal details of surface band structure, and canno...

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New superconducting phase of Bi₂Te₃under pressure above 11 GPa

Cited by 55 publications

References 5 publications

Pressure-induced superconductivity in topological parent compound Bi ₂ Te ₃

Pressure-induced superconductivity in topological parent compound Bi ₂ Te ₃

Realization of insulating state and superconductivity in the Rashba semiconductor BiTeCl

Majorana fermions inch closer to reality

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New superconducting phase of Bi2Te3under pressure above 11 GPa

Cited by 55 publications

References 5 publications

Pressure-induced superconductivity in topological parent compound Bi 2 Te 3

Pressure-induced superconductivity in topological parent compound Bi 2 Te 3

Realization of insulating state and superconductivity in the Rashba semiconductor BiTeCl

Majorana fermions inch closer to reality

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New superconducting phase of Bi₂Te₃under pressure above 11 GPa

Pressure-induced superconductivity in topological parent compound Bi ₂ Te ₃

Pressure-induced superconductivity in topological parent compound Bi ₂ Te ₃