Layer structure superconductor

Revolinsky, E.; Lautenschlager, Eugene P.; Armitage, C.H.

doi:10.1016/0038-1098(63)90358-2

Cited by 53 publications

(31 citation statements)

References 5 publications

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“…The underlying structures are made from stacking X-M-X layers in repeating patterns with inter-layer Van der Waals bonding. The weak Van der Waals interlayer bonding between hexagonal layers of octahedral or trigonal prismatic TMD building blocks allows many polytypes to form.Many of the members in this family exhibit the coexistence/competition between charge density wave (CDW) and superconductivity; where the superconductivity is found to emerge in the vicinity of CDW phase [1,2].The overall electronic phase diagram of these layeredsuperconductors arestrikingly similar to those found in the high-T c cuprates, the organic layered superconductors, and the iron-based pnictides [3].One of the earliest layered TMD materials known to superconduct is 2H-NbSe 2 with a transitiontemperature (T c ) ~7.3K, which is significantly higher than its compatriot superconductors known, where T c is commonly in the range of 2 -4 K. It hosts a quasi-two-dimensional charge density wave (CDW) with CDW critical temperature (T CDW ) ~ 33 K that coexists at local level with superconductivity and also has a strong superconducting gap anisotropy [4]. It is not yet clear whether the observed superconducting gap anisotropy in 2H-NbSe 2 is a result of there being different gaps on different Fermi surface sheets, or it originates elsewhere.…”

Section: Introductionmentioning

confidence: 99%

The effect of Sn intercalation on the superconducting properties of 2H NbSe2

Naik

Pradhan

Bhat³

et al. 2019

Physica C: Superconductivity and its Applications

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2H-NbSe 2 is known to be an archetype layered transitional metal dichalcogenide superconductor with a superconducting transition temperature of 7.3 K.In this article, we investigate the influence of Sn intercalation on superconducting properties of 2H-NbSe 2 . Sn being nonmagnetic and having no outer shell d-electronsunlike transition metals, one naively would presume that its effect on superconducting properties will be very marginal. However, our magnetic and transport studies reveal a significant reduction of both superconducting transition temperature and upper critical field [T c and B C2 (0)] upon Sn intercalation. With a mere 4 mole% Sn intercalation, it is observed that T c and B C2 (0) get suppressed by ~3.5K and 3T, respectively. Werthamer-Helfand-Hohenberg (WHH) analysis of magneto-transport data is performed to estimateB C2 (0). From the low temperature Raman scattering data in the normal phase of intercalated NbSe 2 , it is inferred that the suppression of superconductivity cannot be ascribed to strengthening of charge density wave (CDW)ordering. The effects such as electron-doping induced Fermi surface change and/or disorder scattering upon intercalation are speculated to be at play for the observed phenomena.

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Section: Introductionmentioning

confidence: 99%

The effect of Sn intercalation on the superconducting properties of 2H NbSe2

Naik

Pradhan

Bhat³

et al. 2019

Physica C: Superconductivity and its Applications

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“…Layered transition metal dichalcogenide (TMD) is one of the most important material groups that shows plenty physical phenomena such as charge density waves [13,14], superconductivity [15,16], metal-insulator-transition [17], unsaturate magneto-resistance [18], etc. One of the TMDs, PdTe 2 is an intermetallic compound and is known to become a superconductor below T c =1.7 K [19], which is comparable to other TMD superconductors.…”

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confidence: 99%

Experimental Realization of Type-II Dirac Fermions in a PdTe2 Superconductor

Noh¹,

Jeong²,

Cho³

et al. 2017

Phys. Rev. Lett.

285

212

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A Dirac fermion in a topological Dirac semimetal is a quadruple-degenerate quasi-particle state with a relativistic linear dispersion. Breaking either time-reversal or inversion symmetry turns this system into a Weyl semimetal that hosts double-degenerate Weyl fermion states with opposite chiralities. These two kinds of quasi-particles, although described by a relativistic Dirac equation, do not necessarily obey Lorentz invariance, allowing the existence of so-called type-II fermions. Recent theoretical discovery of type-II Weyl fermions evokes the prediction of type-II Dirac fermions in PtSe 2 -type transition metal dichalcogenides, expecting an experimental confirmation. Here, we report an experimental realization of type-II Dirac fermions in PdTe 2 by angle-resolved photoemission spectroscopy combined with ab-initio band calculations. Our experimental finding makes the first example that has both superconductivity and type-II Dirac fermions, which turns the topological material research into a new phase.

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“…Among metallic TMDs, the stacked trigonal prismatic structure of niobium diselenide (2H-NbSe 2 ) is one of the most studied materials and an ideal system to study phase transitions as functions of temperature and dopings. It has been known for a long time 32,33 that threedimensional stacking structure of 2H-NbSe 2 is metallic at room temperature and undergoes a CDW transition at 33 K before becoming a superconductor 34,35 at 7.2 K although there has been the controversy regarding on the origin of CDW and the competition between CDW and superconducting (SC) states 32,33,[36][37][38][39][40][41][42][43][44][45] . After a few earlier attempts to investigate physical properties of its thin flakes 1,46,47 , a couple of recent works have reported successful isolations of its single layer form on top of various substrates and measure their CDW and SC phase transitions [27][28][29][30][31] .…”

Section: Introductionmentioning

confidence: 99%

Quasiparticle energy bands and Fermi surfaces of monolayer NbSe2

Kim

Son

2017

Phys. Rev. B

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A quasiparticle band structure of a single layer 2H-NbSe2 is reported by using first-principles GW calculation. We show that a self-energy correction increases the width of a partially occupied band and alters its Fermi surface shape when comparing those using conventional mean-field calculation methods. Owing to a broken inversion symmetry in the trigonal prismatic single layer structure, the spin-orbit interaction is included and its impact on the Fermi surface and quasiparticle energy bands are discussed. We also calculate the doping dependent static susceptibilities from the band structures obtained by the mean-field calculation as well as GW calculation with and without spinorbit interactions. A complete tight-binding model is constructed within the three-band third nearest neighbour hoppings and is shown to reproduce our GW quasiparticle energy bands and Fermi surface very well. Considering variations of the Fermi surface shapes depending on self-energy corrections and spin-orbit interactions, we discuss the formations of charge density wave (CDW) with different dielectric environments and their implications on recent controversial experimental results on CDW transition temperatures.

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Layer structure superconductor

Cited by 53 publications

References 5 publications

The effect of Sn intercalation on the superconducting properties of 2H NbSe2

The effect of Sn intercalation on the superconducting properties of 2H NbSe2

Experimental Realization of Type-II Dirac Fermions in a PdTe2 Superconductor

Quasiparticle energy bands and Fermi surfaces of monolayer NbSe2

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