Fermi-crossing Type-II Dirac fermions and topological surface states in NiTe2

Mukherjee, Saumya; Jung, Sung Won; Weber, Sophie F.; Xu, Chunqiang; Qian, Dong; Xu, Xiaofeng; Biswas⃰, Pabitra Kumar; Kim, T. K.; Chapon, Laurent; Watson, M. D.; Neaton, Jeffrey B.; Cacho, Céphise

doi:10.1038/s41598-020-69926-8

Cited by 33 publications

(51 citation statements)

References 29 publications

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“…Those nontrivial band crosses form topological insulator state or topological Dirac semimetal state, contingent upon the same or different angular momentums of the crossing bands respectively. We note that the band inversion along k z is not unique to iron-based superconductors, it occurs ubiquitously in the 1T phase of transition metal dichalcogenides (such as PtTe 2 , PdTe 2 , and NiTe 2 ) [107][108][109]. In principle, topological band structure can be produced in all the iron-based superconductors under sufficient tuning.…”

Section: Topological Band Structurementioning

confidence: 92%

Emergent vortex Majorana zero mode in iron-based superconductors

Kong¹,

Ding²

2020

Acta Phys. Sin.

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The vortex of iron-based superconductors is emerging as a promising platform for Majorana zero mode, owing to a magic integration among intrinsic vortex winding, non-trivial band topology, strong electron-electron correlations, high-Tc superconductivity and the simplification of single material. It overcomes many difficulties suffered in heterostructure-based Majorana platforms, including small topological gap, interfacial contamination, lattice imperfections, and etc. Isolated zero-bias peaks have been found in vortex of several iron-based superconductors. So far, studies from both experimental and theoretical aspects strongly indicate the realization of vortex Majorana zero mode, with a potential to be applied to fault-tolerant quantum computation. By taking Fe(Te,Se) superconductor as an example, here we review the original idea and research progress of Majorana zero modes in this new platform. After introducing the identifications of topological band structure and real zero modes in vortex, we summarize the physics behaviors of vortex Majorana zero modes systematically. First, relying on the behavior of the zero mode wave function and evidence of quasiparticle poisoning, we analyze the mechanism of emergence of vortex Majorana zero modes. Secondly, assisted with some well-established theories, we elaborate the measurements on "Majorana symmetry" and topological nature of vortex Majorana zero modes. After that, we switch from quantum physics to quantum engineering, and analyze the performance of vortex Majorana zero modes under real circumstances, which may potentially benefit the exploration of practical applications in the future. This review follows the physics properties of vortex Majorana zero modes, especially emphasizes the link between phenomena and mechanisms. It provides a chance to bridge the gap between the well-established theories and the newly discovered "iron home" of Majoranas.

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Section: Topological Band Structurementioning

confidence: 92%

Emergent vortex Majorana zero mode in iron-based superconductors

Kong¹,

Ding²

2020

Acta Phys. Sin.

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“…Another plausible origin of the FCPM is related to the Zeeman shift of the proximitized topological surface states of NiTe 2 . Previous studies 23,24 have reported the presence of spin-polarized surface states in NiTe 2 that cross the Fermi level. Here we have used ARPES to examine the detailed fermiology of these surfaces states and estimate their Fermi energy and velocity (Supplementary Sections IX and X).…”

mentioning

confidence: 91%

“…NiTe 2 crystallizes in a CdI 2 -type trigonal crystal structure with the space group P 3m1, which is centrosymmetric 23,24 (Supplementary Section I). This 2D van der Waals material is a type-II Dirac semimetal that hosts several spin-helical topological surface states 23,24 . As discussed later, these surface states play a key role in the JDE.…”

mentioning

confidence: 99%

Josephson diode effect from Cooper pair momentum in a topological semimetal

et al. 2022

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Cooper pairs in non-centrosymmetric superconductors can acquire finite centre-of-mass momentum in the presence of an external magnetic field. Recent theory predicts that such finite-momentum pairing can lead to an asymmetric critical current, where a dissipationless supercurrent can flow along one direction but not in the opposite one. Here we report the discovery of a giant Josephson diode effect in Josephson junctions formed from a type-II Dirac semimetal, NiTe2. A distinguishing feature is that the asymmetry in the critical current depends sensitively on the magnitude and direction of an applied magnetic field and achieves its maximum value when the magnetic field is perpendicular to the current and is of the order of just 10 mT. Moreover, the asymmetry changes sign several times with an increasing field. These characteristic features are accounted for by a model based on finite-momentum Cooper pairing that largely originates from the Zeeman shift of spin-helical topological surface states. The finite pairing momentum is further established, and its value determined, from the evolution of the interference pattern under an in-plane magnetic field. The observed giant magnitude of the asymmetry in critical current and the clear exposition of its underlying mechanism paves the way to build novel superconducting computing devices using the Josephson diode effect.

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“…Among the family of TMD materials, the layered binary tellurides of Co and Ni (CoTe 2 and NiTe 2 ) have been reported many times for their different physical properties. ,− Especially, since the discovery of 1 T -NiTe 2 as a topological material having Dirac semimetallic properties with the Dirac fermions close to the Fermi energy, it has provided a new platform to study the type-II Dirac. − …”

Section: Introductionmentioning

confidence: 99%

Evolution of Temperature-Induced Isostructural Phase Transition in a Newly Grown Layered FeTe₂ Single Crystal

Feng

Pal

et al. 2021

Chem. Mater.

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Layered FeTe 2 (l-FeTe 2 ) was supposed to be one of the most important compounds in the family of two-dimensional transition-metal dichalcogenides (2D TMDs) owing to the importance of an iron element and its predicted novel physical phenomena. However, 2D layered FeTe 2 is rarely reported because of its tendency to be stabilized in three-dimensional marcasite phase structures. Here, we report, for the first time, a pure and large-size l-FeTe 2 single crystal synthesized successfully in a P3̅ m1 hexagonal space group using a solid-state reaction method. Thermoanalysis and X-ray diffraction (XRD) data after annealing at different temperatures indicate that l-FeTe 2 is a metastable material. The results of electrical transport, magnetization, and in situ low-temperature XRD measurements confirm that l-FeTe 2 undergoes a first-order isostructural phase transition from 120 to 150 K, and we established a detailed correlation among these properties of l-FeTe 2 . l-FeTe 2 transforms from an insulating to metallic state at 120 K where the phase transition completes. In addition, the Shubnikov−de Haas (SdH) oscillation phenomenon is observed under a high magnetic field at 4 K.

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Fermi-crossing Type-II Dirac fermions and topological surface states in NiTe2

Cited by 33 publications

References 29 publications

Emergent vortex Majorana zero mode in iron-based superconductors

Emergent vortex Majorana zero mode in iron-based superconductors

Josephson diode effect from Cooper pair momentum in a topological semimetal

Evolution of Temperature-Induced Isostructural Phase Transition in a Newly Grown Layered FeTe₂ Single Crystal

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Fermi-crossing Type-II Dirac fermions and topological surface states in NiTe2

Cited by 33 publications

References 29 publications

Emergent vortex Majorana zero mode in iron-based superconductors

Emergent vortex Majorana zero mode in iron-based superconductors

Josephson diode effect from Cooper pair momentum in a topological semimetal

Evolution of Temperature-Induced Isostructural Phase Transition in a Newly Grown Layered FeTe2 Single Crystal

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Evolution of Temperature-Induced Isostructural Phase Transition in a Newly Grown Layered FeTe₂ Single Crystal