Indium Substitution Effect on the Topological Crystalline Insulator Family (Pb1−xSnx)1−yInyTe: Topological and Superconducting Properties

Zhong, Ruidan; Schneeloch, John; Li, Qiang; Ku, Wei; Tranquada, J. M.; Gu, Genda

doi:10.3390/cryst7020055

Cited by 25 publications

(14 citation statements)

References 78 publications

(130 reference statements)

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“…However, it showed superconductivity as the concentration went to 10%. The transition temperature T c was 3~5 K, which was close to that of Cu-doped TIs [ 99 , 103 ]. In recent years, there have been many articles about the superconductivity of In-doped TI.…”

Section: Preparation and Doping Of Timentioning

confidence: 65%

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The Property, Preparation and Application of Topological Insulators: A Review

et al. 2017

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Topological insulator (TI), a promising quantum and semiconductor material, has gapless surface state and narrow bulk band gap. Firstly, the properties, classifications and compounds of TI are introduced. Secondly, the preparation and doping of TI are assessed. Some results are listed. (1) Although various preparation methods are used to improve the crystal quality of the TI, it cannot reach the industrialization. Fermi level regulation still faces challenges; (2) The carrier type and lattice of TI are affected by non-magnetic impurities. The most promising property is the superconductivity at low temperature; (3) Magnetic impurities can destroy the time-reversal symmetry of the TI surface, which opens the band gap on the TI surface resulting in some novel physical effects such as quantum anomalous Hall effect (QAHE). Thirdly, this paper summarizes various applications of TI including photodetector, magnetic device, field-effect transistor (FET), laser, and so on. Furthermore, many of their parameters are compared based on TI and some common materials. It is found that TI-based devices exhibit excellent performance, but some parameters such as signal to noise ratio (S/N) are still lower than other materials. Finally, its advantages, challenges and future prospects are discussed. Overall, this paper provides an opportunity to improve crystal quality, doping regulation and application of TI.

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Section: Preparation and Doping Of Timentioning

confidence: 65%

“…Therefore, they had little effect on the resistivity. However, In doping influenced the structure and transmission properties of the TCIs [ 103 , 104 ]. For example, different x had various effects on In x (Pb 1−y Sn y ) 1−x Te [ 104 ].…”

Section: Preparation and Doping Of Timentioning

confidence: 99%

The Property, Preparation and Application of Topological Insulators: A Review

et al. 2017

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“…In addition, we have In dopants; in the related com- pound Sn 1−x In x Te, each In ion appears to donate one electron, but these electrons only gradually delocalize and become mobile with increasing x 53 . In the present case, the added carriers must be involved in tuning the superconductivity; however, the normal-state resistivity is very large, and has a nonmetallic temperature dependence 22,27 . To illustrate this, in Fig.…”

mentioning

confidence: 89%

“…Magnetization and resistivity were measured using a Quantum Design magnetic properties measurement system and physical properties measurement system, respectively. The sample with no In is a TCI 19,22,27 . It shows a weakly metallic behavior and is not superconducting down to 1.8 K. The x = 0.3 sample is superconducting with a T c of 4.7 K, as determined from the onset of diamagnetism and zero resistivity, as shown in Fig.…”

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confidence: 99%

Unusual phonon density of states and response to the superconducting transition in the In-doped topological crystalline insulator Pb0.5Sn0.5Te

et al. 2018

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We present inelastic neutron scattering results of phonons in (Pb0.5Sn0.5)1−xInxTe powders, with x = 0 and 0.3. The x = 0 sample is a topological crystalline insulator, and the x = 0.3 sample is a superconductor with a bulk superconducting transition temperature Tc of 4.7 K. In both samples, we observe unexpected van Hove singularities in the phonon density of states at energies of 1-2.5 meV, suggestive of local modes. On cooling the superconducting sample through Tc, there is an enhancement of these features for energies below twice the superconducting-gap energy. We further note that the superconductivity in (Pb0.5Sn0.5)1−xInxTe occurs in samples with normal-state resistivities of order 10 mΩ cm, indicative of bad-metal behavior. Calculations based on density functional theory suggest that the superconductivity is easily explainable in terms of electron-phonon coupling; however, they completely miss the low-frequency modes and do not explain the large resistivity. While the bulk superconducting state of (Pb0.5Sn0.5)0.7In0.3Te appears to be driven by phonons, a proper understanding will require ideas beyond simple BCS theory.Topological insulators (TIs) represent an exotic state of matter in which the bulk is insulating but the surface is metallic 1,2 . The topological state is protected by the time-reversal symmetry 1 . By including a certain crystal point group symmetry instead of time reversal, topological crystalline insulators (TCIs), a state analogous to TIs, was also proposed 3,4 . In particular, it was predicted that compounds such as SnTe might be TCIs 5 , and the key features, including the inverted character of bands near the chemical potential 6,7 and surface states within the band gap that are protected from back-scattering 8,9 , were soon verified.These developments have also spurred renewed interest in topological superconductors, as such materials may exhibit gapless surface states that could be beneficial for quantum computing 1-3 . A common aspect of TCIs is strong spin-orbit coupling in the atomic states contributing to the valence and conduction bands, and this is a useful ingredient for obtaining the unusual pairing symmetry expected for a topological superconductor. Hence, there is interest in seeing whether doping TCIs can induce superconductivity with a topological nature. Indeed, one can make SnTe superconducting by introducing In, and a point-contact study found evidence of surface Andreev bound states 10 , though thermodynamic studies suggest a fully gapped superconducting state [11][12][13] .SnTe is a compound that has the rocksalt structure despite the fact that the component elements do not all form closed-shell ions. A consequence is a strong intrinsic electron-phonon coupling 14,15 , which leads to a ferro-electric phase transition in SnTe 16,17 . One way to suppress the ferroelectric transition is to substitute Pb for Sn, and it has been estimated that the transition should hit 0 K for Pb y Sn 1−y Te with y ≈ 0.5 18 . At this Pb concentration the system becomes a TCI 19 . Also, s...

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“…Furthermore, the Fermi level can be modulated by doping In, which can realize not only highmobility transport in the semimetal states but also superconductivity [23,24]. These novel electronic states in PbTe-SnTe system doped with In have been extensively studied in a bulk crystal form.…”

Section: Main Textmentioning

confidence: 99%

Versatile electronic states in epitaxial thin films of (Sn-Pb-In)Te: From topological crystalline insulator and polar semimetal to superconductor

Yoshimi

Masuko

Ogawa

et al. 2021

Phys. Rev. Materials

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Epitaxial thin films of (SnxPb1-x)1-yInyTe were successfully grown by molecular-beam-epitaxy (MBE) in a broad range of compositions (0 ≤ x ≤ 1, 0 ≤ y ≤0.23). We investigated electronic phases of the films by the measurements of electrical transport and optical second harmonic generation. In this system, one can control the inversion of band gap, the electric polarization that breaks the inversion symmetry, and the Fermi level position by tuning the Pb/Sn ratio and In composition. A plethora of topological electronic phases are expected to emerge, such as topological crystalline insulator, topological semimetal, and superconductivity. For the samples with large Sn compositions (x > 0.5), hole density increases with In composition (y), which results in the appearance of superconductivity. On the other hand, for those with small Sn compositions (x < 0.5), increase in In composition reduces the hole density and changes the carrier type from ptype to n-type. In a narrow region centered at (x, y) = (0.16, 0.07) where the n-type carriers are slightly doped, charge transport with high mobility exceeding 5,000 cm 2 V -1 s -1 shows up, representing the possible semimetal states. In those samples, the optical second harmonic generation measurement shows the breaking of inversion symmetry along the out-of-plane [111] direction, which ensures the presence of polar semimetal state. The thin films of (SnxPb1-x)1-yInyTe materials systems with a variety of electronic states would become a promising materials platform for the exploration of novel quantum phenomena.

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Indium Substitution Effect on the Topological Crystalline Insulator Family (Pb1−xSnx)1−yInyTe: Topological and Superconducting Properties

Cited by 25 publications

References 78 publications

The Property, Preparation and Application of Topological Insulators: A Review

The Property, Preparation and Application of Topological Insulators: A Review

Unusual phonon density of states and response to the superconducting transition in the In-doped topological crystalline insulator Pb0.5Sn0.5Te

Versatile electronic states in epitaxial thin films of (Sn-Pb-In)Te: From topological crystalline insulator and polar semimetal to superconductor

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