Magnetic tunnel junctions with MgO-EuO composite tunnel barriers

Miao, Guo‐Xing; Moodera, Jagadeesh S.

doi:10.1103/physrevb.85.144424

Cited by 33 publications

(40 citation statements)

References 30 publications

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“…In general, the exact number and position of minima depends on the relative size and shape of the various FSs. For example, from the similar size of the FSs at and M in FeSe 0.55 Te 0.45 , 19 one should expect only 4 minima in the scattering function, which is consistent with the 4 gap minima reported in a angle-resolved specific heat study. 28 Assuming a non-negligible interband scattering, the effective gap measured by angle-resolved specific heat and other probes sensitive to residual density of states should be anisotropic in our simulation, even if the SC pairing gap itself is isotropic.…”

confidence: 75%

Angle-resolved photoemission studies of the superconducting gap symmetry in Fe-based superconductors

et al. 2012

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The superconducting gap is the fundamental parameter that characterizes the superconducting state, and its symmetry is a direct consequence of the mechanism responsible for Cooper pairing. Here we discuss about angle-resolved photoemission spectroscopy measurements of the superconducting gap in the Fe-based high-temperature superconductors. We show that the superconducting gap is Fermi surface dependent and nodeless with small anisotropy, or more precisely, a function of the momentum location in the Brillouin zone. We show that while this observation seems inconsistent with weak coupling approaches for superconductivity in these materials, it is well supported by strong coupling models and global superconducting gaps. We also suggest that a smaller lifetime of the superconducting Cooper pairs induced by the momentum dependent interband scattering inherent to these materials could affect the residual density of states at low energies, which is critical for a proper evaluation of the superconducting gap

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confidence: 75%

Angle-resolved photoemission studies of the superconducting gap symmetry in Fe-based superconductors

et al. 2012

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“…In this picture, the J 3 is very sensitive to the hybridization due to the size of the p z orbital and the distance of the Se/Te atoms from the Fe-layers. Interestingly, a possible hybridization between Fe 3d and p z states has also been noted in the cousin FeSe 0.45 Te 0.55 system [6], which is also characterized by a large J 3 AFM coupling.…”

mentioning

confidence: 78%

“…with maximum T c = 32 K [1,2] changed the landscape of Fe-based superconductivity. Unlike the other Fe-based superconductors, for which both hole-like and electron-like Fermi surfaces (FSs) are observed simultaneously [3][4][5][6][7][8][9], these new materials are characterized by the absence of hole-like FS [10][11][12][13]. As with most of the other materials though, nearly isotropic superconducting (SC) gaps in the strong coupling regime are found on the observed FSs [11][12][13], suggesting a possible universal pairing mechanism for all Febased superconductors.…”

mentioning

confidence: 99%

Three Dimensionality and Orbital Characters of the Fermi Surface in(Tl,Rb)yFe2−xSe2

Liu

Richard

et al. 2012

Phys. Rev. Lett.

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We report a comprehensive angle-resolved photoemission spectroscopy study of the tridimensional electronic bands in the recently discovered Fe selenide superconductor ðTl; RbÞ y Fe 2Àx Se 2 (T c ¼ 32 K). We determined the orbital characters and the k z dependence of the low energy electronic structure by tuning the polarization and the energy of the incident photons. We observed a small 3D electron Fermi surface pocket near the Brillouin zone center and a 2D like electron Fermi surface pocket near the zone boundary. The photon energy dependence, the polarization analysis and the local-density approximation calculations suggest a significant contribution from the Se 4p z and Fe 3d xy orbitals to the small electron pocket. We argue that the emergence of Se 4p z states might be the cause of the different magnetic properties between Fe chalcogenides and Fe pnictides.

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“…The electronic structure investigations of superconducting iron chalcogenides, both theoretical [24,25,26,27,28] and experimental [8,25,31,30,32], have shown that the multi-gap nature of their SC may be connected with interband interactions between the holelike β and electronlike δ Fermi surface (FS) sheets. In particular, SC can be mediated by antiferromagnetic spin fluctuations (SF), observed experimentally by e.g.…”

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confidence: 99%

Strain effects on the electronic structure of the FeSe0.5Te0.5 superconductor

Winiarski¹,

Samsel‐Czekała²,

Ciechan³

2013

Journal of Alloys and Compounds

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The electronic structure of the strained FeSe 0.5 Te 0.5 superconductor has been investigated from first principles. Our calculation results indicate that the influence of hydrostatic, biaxial or uniaxial compressive stress on the density of states at the Fermi level is insignificant. The overall shape of the Fermisurface (FS) nesting function for FeSe 0.5 Te 0.5 at ambient pressure resembles that of its parent compound, FeSe, but under the ab-plane compressive strain. In these two systems, changes of their FSs under various stress conditions are qualitatively almost the same. However, in FeSe 0.5 Te 0.5 the intensity of the perfect Q = (0.5, 0.5) × (2π/a) nesting vector is more diminished. These findings are in good agreement with former experimental data and support the idea of spin-fluctuation mediated superconductivity in iron chalcogenides.

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Magnetic tunnel junctions with MgO-EuO composite tunnel barriers

Cited by 33 publications

References 30 publications

Angle-resolved photoemission studies of the superconducting gap symmetry in Fe-based superconductors

Angle-resolved photoemission studies of the superconducting gap symmetry in Fe-based superconductors

Three Dimensionality and Orbital Characters of the Fermi Surface in(Tl,Rb)yFe2−xSe2

Strain effects on the electronic structure of the FeSe0.5Te0.5 superconductor

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