Phonons and superconductivity in fcc and dhcp lanthanum

Baǧcı, S.; Tütüncü, H. M.; Duman, S.; Srivastava, G. P.

doi:10.1103/physrevb.81.144507

Cited by 34 publications

(30 citation statements)

References 36 publications

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“…We strongly believe that these phonon anomalies play an important role in developing superconductivity in the Heusler compound YPd 2 Sn since a similar observation has been made for several superconductors. [27][28][29][30][31] There are three optical branches in the high-frequency region of the phonon spectrum. These phonon branches are less dispersive than the optical phonon branches in the lowfrequency region.…”

Section: B Electron-phonon Interaction and Superconductivitymentioning

confidence: 99%

Phonon anomalies and superconductivity in the Heusler compound YPd2Sn

Tütüncü

Srivastava

2014

Journal of Applied Physics

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We have studied the structural and electronic properties of YPd2Sn in the Heusler structure using a generalized gradient approximation of the density functional theory and the ab initio pseudopotential method. The electronic results indicate that the density of states at the Fermi level is primarily derived from Pd d states, which hybridize with Y d and Sn p states. Using our structural and electronic results, phonons and electron-phonon interactions have been studied by employing a linear response approach based on the density functional theory. Phonon anomalies have been observed for transverse acoustic branches along the [110] direction. This anomalous dispersion is merely a consequence of the strong coupling. By integrating the Eliashberg spectral function, the average electron-phonon coupling parameter is found to be λ = 0.99. Using this value, the superconducting critical temperature is calculated to be 4.12 K, in good accordance with the recent experimental value of 4.7 K.

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Section: B Electron-phonon Interaction and Superconductivitymentioning

confidence: 99%

Phonon anomalies and superconductivity in the Heusler compound YPd2Sn

Tütüncü

Srivastava

2014

Journal of Applied Physics

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“…3) via dn tun /dt = −n tun /τ + I/(eV). [14] Assuming the steady state condition dn tun /dt = 0, n tun can be estimated from V. Then, n tun has to be compared to n th as derived from the normal state DOS, which is assumed to be constantly N (0) around E F , [24] and calculated (Fig. 3) lifetimes.…”

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confidence: 99%

Tunneling into thin superconducting films: Interface-induced quasiparticle lifetime reduction

et al. 2016

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Scanning tunneling spectroscopy measurements of superconducting thin lanthanum films grown on a normal metal tungsten substrate reveal an extraordinarily large broadening of the coherence peaks. The observed broadening corresponds to very short electron-like quasiparticle lifetimes in the tunneling process. A thorough analysis considering the different relaxation processes reveals that the dominant mechanism is an efficient quasiparticle relaxation at the interface between the superconducting film and the underlying substrate. This process is of general relevance to scanning tunneling spectroscopy studies on thin superconducting films and enables measurements of film thicknesses via a spectroscopic method.

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“…The linear response method [36,41,42] and Migdal-Eliashberg theory [37][38][39][40] have been used to calculate the electron-phonon coupling matrix, the average electronphonon coupling parameter (λ) and the superconducting transition temperature (T c ). According to this theory, T c depends on the effective screened Coulomb repulsion constant (µ * ) and the Eliashberg spectral function (α 2 F (ω)).…”

Section: Methodsmentioning

confidence: 99%

“…The calculation of the Eliashberg spectral function (α 2 F (ω)) has been done using a very fine (24 × 24 × 24) k points mesh in performing the Fermi surface average of the electron-phonon matrix elements. The electron-phonon mass enhancement parameter λ is given as [41,42] …”

Section: Methodsmentioning

confidence: 99%

“…Finally, electron-phonon matrix elements for both materials are calculated using the linear response method [36] and the Migdal-Eliashberg approach [37,38]. The phonon dispersion relations and the electron-phonon matrix elements are then used to determine the Eliashberg spectral function [37][38][39][40][41][42], from which the electron-phonon coupling parameter is calculated. Finally, the superconducting parameters for both materials are presented and compared with each other, and an explanation has been made for observed differences.…”

Section: Introductionmentioning

confidence: 99%

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Theoretical investigation of superconductivity in SrAuSi3 and SrAu2Si2

Arslan

Karaca

Tütüncü

et al. 2016

Journal of Physics and Chemistry of Solids

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The structural and electronic properties of BaNiSn 3 -type SrAuSi 3 and ThCr 2 Si 2 -type SrAu 2 Si 2 have been investigated by using the planewave pseudopotential method and the density functional theory. The electronic structures and phonon dispersion relations of these two materials have been analyzed with and without the inclusion of spin-orbit interaction, and similarities and differences highlighted. By integrating the Eliashberg spectral function α 2 F(ω), the average electron-phonon coupling parameter is determined to be λ = 0.47 for SrAuSi 3 and 0.42 for SrAu 2 Si 2 . The largest contribution to the electron-phonon coupling for SrAuSi 3 comes from the Si p electrons near the Fermi energy and Si-related vibrations. Using a reasonable value of µ * = 0.12 for the effective Coulomb repulsion parameter, the superconducting critical temperature T c for SrAuSi 3 is found to be 1.47 K which compares very well with its experimental value of 1.54 K.

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Phonons and superconductivity in fcc and dhcp lanthanum

Cited by 34 publications

References 36 publications

Phonon anomalies and superconductivity in the Heusler compound YPd2Sn

Phonon anomalies and superconductivity in the Heusler compound YPd2Sn

Tunneling into thin superconducting films: Interface-induced quasiparticle lifetime reduction

Theoretical investigation of superconductivity in SrAuSi3 and SrAu2Si2

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