Electron–phonon superconductivity in BaSn<sub>5</sub>

Billington, David P.; Ernsting, David; Millichamp, Thomas E.; Dugdale, Stephen B

doi:10.1080/14786435.2015.1040480

Cited by 5 publications

(5 citation statements)

References 18 publications

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“…If we assume the dominant renormalisation comes from the coupling between the electrons and the lattice, such that we can say λ = λ ep , then this value can be directly compared to the value of λ ep of 0.62 in-225 ferred from experiment [15]. Whilst there is reasonable agreement, it should be noted that experimental mea- surements of the Sommerfeld coefficient are incredibly challenging but the higher experimental value for λ ep may point to the electrons coupling more strongly to 230 special modes as has been seen previously [31,32].…”

mentioning

confidence: 96%

Enhanced superconductivity in the high pressure phase of SnAs studied from first principles

Reddy

Kanchana

Millichamp³

et al. 2017

Physica B: Condensed Matter

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General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. AbstractFirst principles calculations are performed using density functional theory and density functional perturbation theory for SnAs. Total energy calculations show the first order phase transition from an NaCl structure to a CsCl one at around 37 GPa, which is also confirmed from enthalpy calculations and agrees well with experimental work. Calculations of the phonon structure and hence the electron-phonon coupling, λ ep , and superconducting transition temperature, T c , across the phase diagram are performed. These calculations give an ambient pressure T c , in the NaCl structure, of 3.08 K, in good agreement with experiment whilst at the transition pressure, in the CsCl structure, a drastically increased value of T c = 12.2 K is found. Calculations also show a dramatic increase in the electronic density of states at this pressure. The lowest energy acoustic phonon branch in each structure also demonstrates some softening effects. Electronic structure calculations of the Fermi surface in both phases are presented for the first time as well as further calculations of the generalised susceptibility with the inclusion of matrix elements. These calculations indicate that the softening is not derived from Fermi surface nesting and it is concluded to be due to a wavevector-dependent enhancement of the electron-phonon coupling.

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confidence: 96%

Enhanced superconductivity in the high pressure phase of SnAs studied from first principles

Reddy

Kanchana

Millichamp³

et al. 2017

Physica B: Condensed Matter

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“…There are two ELF domains with η > 0.73: one “torus” k spread around the P atoms in the xy plane and a second small ELF attractor l oriented along the z ‐axis toward the other one from a neighboring P‐atom, but they are isolated by a separating region. Such closely located and oriented opposite to each other lone pairs have been found in SrCo 2 Si 2 , Ca(Sr)Co 2 Ge 2 as well as in the electron–phonon superconductor BaSn 5 , structurally close related to MgB 2 . These lone pairs at the Sn atoms in BaSn 5 originate from the p z orbitals, which form the flat band region at E F and are responsible for superconductivity (van Hove scenario) .…”

Section: Resultsmentioning

confidence: 74%

Structural instability and superconductivity in the solid solution SrNi₂(P_1−xGe_x)₂

Hlukhyy

Hoffmann

Grinenko

et al. 2016

Physica Status Solidi (b)

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The solid solution SrNi2(P1−xGex)2 with ThCr2Si2‐type structure has been synthesized over the whole composition range by high‐temperature solid state reactions. Structure investigations were performed using X‐ray diffraction (XRD) methods. In addition, in situ temperature‐dependent powder XRD measurements down to 10 K were carried out for two SrNi2(P1−xGex)2 samples with x = 0.110(3) and 0.212(3), which indicate a temperature‐induced collapse of the structure of the first compound around 200 K. For both samples, superconductivity was detected above 1.8 K by magnetic, resistivity, and heat capacity measurements (TC ∼ 3.0 and 2.4 K, respectively). The crystal chemistry and the chemical bonding in the superconducting compounds are discussed in terms of linear muffin‐tin orbital (LMTO) band structure calculations including density of states (DOS), crystal orbital Hamilton populations (COHPs), and a topological analysis using the electron localization function (ELF).

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“…At 1.85 GPa, the P 4̅2 1 m phase with a complex three-dimensional framework formed by Sn atoms transformed into the phase P 6/ mmm ( Z = 1) in which Sn atoms form a layered structure. The P 6/ mmm structure can also be seen in BaSn 5 . − In P 6/ mmm -NaSn 5 , Na atoms are located at the Wyckoff 1b sites. Two inequivalent Sn1 and Sn2 atoms are located at the Wyckoff 4h and 1a sites, respectively.…”

Section: Resultsmentioning

confidence: 97%

“…The P6/mmm structure can also be seen in BaSn5. 37,38,39 In P6/mmm-NaSn5, Na atoms located at the Wyckoff 1b sites. Two inequivalent Sn1 and Sn2 atoms located at the Wyckoff 4h and 1a sites.…”

Section: Structural Phase Transitionmentioning

confidence: 99%

Pressure-Induced Structural Phase Transition and Superconductivity in NaSn₅

Hao

Huang

et al. 2019

Inorg. Chem.

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The structural and electronic properties of tin-rich compound NaSn5 were investigated under pressure up to 10 GPa based on the evolutionary algorithm (EA) technique coupled with first-principles total energy calculations. Upon compression, the known metallic tetragonal P-421m phase transforms into a metallic hexagonal P6/mmm phase at 1.85 GPa accompanied by an unusual change of existing form of Sn atoms. The P6/mmm phase can be interpreted as a quasi-layered sandwich structure with two Sn layers and one sodium layer. The presence of softening phonon modes and the existence of Fermi pockets together with the obvious Fermi surface nesting indicate a strong electron-phonon coupling (EPC) and thus potential superconductivity in P6/mmm phase. The strong EPC in P6/mmm phase is mainly attributed to the phonons from Sn1 atoms together with electrons from the Sn1-py and Sn1-pz states. The calculated superconducting critical temperature Tc of the P6/mmm phase is 5.91 K at 1.85 GPa. This study provides a new clue for designing intercalated compounds with superconductivity.

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Electron–phonon superconductivity in BaSn₅

Cited by 5 publications

References 18 publications

Enhanced superconductivity in the high pressure phase of SnAs studied from first principles

Enhanced superconductivity in the high pressure phase of SnAs studied from first principles

Structural instability and superconductivity in the solid solution SrNi₂(P_1−xGe_x)₂

Pressure-Induced Structural Phase Transition and Superconductivity in NaSn₅

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Electron–phonon superconductivity in BaSn5

Cited by 5 publications

References 18 publications

Enhanced superconductivity in the high pressure phase of SnAs studied from first principles

Enhanced superconductivity in the high pressure phase of SnAs studied from first principles

Structural instability and superconductivity in the solid solution SrNi2(P1−xGex)2

Pressure-Induced Structural Phase Transition and Superconductivity in NaSn5

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Electron–phonon superconductivity in BaSn₅

Structural instability and superconductivity in the solid solution SrNi₂(P_1−xGe_x)₂

Pressure-Induced Structural Phase Transition and Superconductivity in NaSn₅