Experimental realization of a topological crystalline insulator in SnTe

Tanaka, Yukio; Ren, Zhi; Sato, Takafumi; Nakayama, K.; Souma, S.; Takahashi, Takashi; Segawa, Kouji; Ando, Yoichi

doi:10.1038/nphys2442

Cited by 898 publications

(944 citation statements)

References 23 publications

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“…Since the discovery of the topological crystalline insulator nature of SnTe in 2012 by Tanaka et al, 25 this material is attracting significant attention as a new type of topological material.…”

Section: Introductionmentioning

confidence: 99%

Superconducting Sn_1–xIn_xTe Nanoplates

Sasaki

Ando

2015

Crystal Growth & Design

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ABSTRACT:Recently, the search for Majorana fermions has become one of the most prominent subjects in condensed matter physics. This search involves explorations of new materials and hence offers interesting opportunities for chemistry. Theoretically, Majorana fermions may reside in various types of topological superconductor materials, and superconducting Sn1-xInxTe, which is a doped topological crystalline insulator, is one of the promising candidates to harbor Majorana fermions. Here, we report the first successful growth of superconducting Sn1-xInxTe nanoplates on Si substrates by a simple vapor transport method without employing any catalyst. We observed robust superconducting transitions in those nanoplates after device fabrication and found that the relation between the critical temperature and the carrier density is consistent with that of bulk single crystals, suggesting that the superconducting properties of the nanoplate devices are essentially the same as those of bulk crystals. With the help of nanofabrication, those nanoplates would prove useful for elucidating the potentially topological nature of superconductivity in Sn1-xInxTe to harbor Majorana fermions and thereby contribute to the future quantum technologies.2

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Section: Introductionmentioning

confidence: 99%

Superconducting Sn_1–xIn_xTe Nanoplates

Sasaki

Ando

2015

Crystal Growth & Design

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“…1,2 Hole-doped SnTe is also often considered a model system for superconductivity in a rock-salt type small band gap semiconductor. [3][4][5][6][7][8] It is known, however, that SnTe shows very different superconducting T c 's when self-hole-doped (i.e.…”

Section: Introductionmentioning

confidence: 99%

Anomalous composition dependence of the superconductivity in In-doped SnTe

et al. 2016

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We report a reinvestigation of superconducting Sn1−xInxTe at both low and high In doping levels. Considering the system over a broad composition range in a single study allows us to characterize a significant change in the properties as a function of x : the system evolves from a weakly coupled p-type superconductor to a strongly coupled n-type superconductor with increasing indium content. Hall Effect measurements show that the carrier density does not vary monotonically with Indium content; a change from p-type to n-type is observed near 10% In-doping. This is contrary to expectations dictating that In should be a p-type dopant in semiconducting SnTe because it has one less valance electron than Sn. A crystallographic search for point defects at high x indicates that the material remains ideal NaCl-type over a wide composition range. Density functional theory calculations for In-doped SnTe support a picture where In does not act as a trivial hole dopant, but instead forms a distinct, partly filled In 5s -Te 5p hybridized state centered around EF , which is very different from what is seen for other nominal hole dopants such as Na, Ag, and vacant Sn sites.

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“…The effective tight-binding model (3) describes this phase with the parameters A = 2.5 eVÅ, B = 9.0 eVÅ 2 , M = 5.08 eV, and the lattice constant a = 4.35Å [25], implying that the velocity of the dislocation modes is v = A/ = 4.3×10 5 m/s, while the localization length λ ∼ B/(12Ba −2 − M) 4.8Å [26]. The enhanced density of states near the dislocation line in a non-TBI [27][28][29][30] should be observable by local probes, such as scanning tunneling microscopy, where the dislocation reaches the crystal surface. The surface states hybridize with the dislocation modes, and the precise local redistribution of the increased density of states can be modeled for the specific experimental situation using our theory.…”

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Interplay between electronic topology and crystal symmetry: Dislocation-line modes in topological band insulators

et al. 2014

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We elucidate the general rule governing the response of dislocation lines in three-dimensional topological band insulators. According to this K-b-t rule, the lattice topology, represented by dislocation lines oriented in direction t with Burgers vector b, combines with the electronic-band topology, characterized by the band-inversion momentum K inv , to produce gapless propagating modes when the plane orthogonal to the dislocation line features a band inversion with a nontrivial ensuing flux = K inv · b(mod 2π ). Although it has already been discovered by Ran et al. [Nat. Phys. 5, 298 (2009)] that dislocation lines host propagating modes, the exact mechanism of their appearance in conjunction with the crystal symmetries of a topological state is provided by the K-b-t rule. Finally, we discuss possible experimentally consequential examples in which the modes are oblivious to the direction of propagation, such as the recently proposed topologically insulating state in electron-doped BaBiO 3 . Topological band insulators (TBIs) represent a new class of quantum materials that, due to the presence of time-reversal symmetry (TRS), feature an insulating bulk band gap together with metallic edge or surface states protected by a Z 2 topological invariant [1][2][3][4]. This Z 2 classification of TBIs is a part of the classification of free gapped fermion matter in the presence of the fundamental antiunitary time-reversal and particle-hole symmetries, the so-called tenfold way [5][6][7]. On the other hand, topologically insulating crystals break continuous translational and rotational symmetries down to discrete symmetries mathematically characterized by the space groups. By considering the crystal symmetries, an extra layer in this Z 2 classification of TBIs has been recently uncovered [8]. This space group classification of TBIs results in the enrichment of the tenfold way with extra phases, such as crystalline (or "valley") phases [9] and translationally active phases, the latter featuring an odd number of band inversions at non-points in the Brillouin zone (BZ) [8,10]. Dislocations are of central interest in this endeavor, being the topological defects exclusively related to the lattice translations. In two dimensions (2D), the role of these lattice defects has been recently elucidated in TBIs [10,11], as well as in topological superconductors [12,13] and interacting topological states [14][15][16]. In particular, it has been shown that these lattice defects in two-dimensional TBIs act as probes of distinct topological states through binding of the localized zero-energy modes [10].Although early on it was identified that in three-dimensional TBIs dislocation lines support propagating helical modes [17], the precise role of dislocations has not been explored thoroughly [18][19][20]. In particular, the relation between the lattice symmetry and the electronic topology, as well as the characterization of these topological states through the response of the dislocation lines, still needs to be addressed. Dislocations in thr...

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Experimental realization of a topological crystalline insulator in SnTe

Cited by 898 publications

References 23 publications

Superconducting Sn_1–xIn_xTe Nanoplates

Superconducting Sn_1–xIn_xTe Nanoplates

Anomalous composition dependence of the superconductivity in In-doped SnTe

Interplay between electronic topology and crystal symmetry: Dislocation-line modes in topological band insulators

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Experimental realization of a topological crystalline insulator in SnTe

Cited by 898 publications

References 23 publications

Superconducting Sn1–xInxTe Nanoplates

Superconducting Sn1–xInxTe Nanoplates

Anomalous composition dependence of the superconductivity in In-doped SnTe

Interplay between electronic topology and crystal symmetry: Dislocation-line modes in topological band insulators

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Superconducting Sn_1–xIn_xTe Nanoplates

Superconducting Sn_1–xIn_xTe Nanoplates