Atomic structure of Al-GaAs(110) interfaces

Yi, Jae‐Yel; Bernholc, J.

doi:10.1103/physrevlett.69.486

Cited by 33 publications

(53 citation statements)

References 33 publications

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“…3(h)). As the d xy band heavily renormalizes compared to the d xz /d yz bands, it is shallower and hardly resolved with weaker intensity [28]. In Cut#1 (Fig.…”

Section: (D)mentioning

confidence: 99%

Topological nature of theFeSe0.5Te0.5superconductor

et al. 2015

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We demonstrate, using first-principles calculations, that the electronic structure of FeSe1−xTex (x=0.5) is topologically non-trivial, characterized by an odd Z2 invariant and Dirac cone type surface states, in sharp contrast to the end member FeSe (x=0). This topological state is induced by the enhanced three-dimensionality and spin-orbit coupling due to Te substitution (compared to FeSe), characterized by a band inversion at the Z point of the Brillouin zone, which is confirmed by our ARPES measurements. The results suggest that the surface of FeSe0.5Te0.5 may support a non-trivial superconducting channel in proximity to the bulk.PACS numbers: 74.70.Xa, Among the Fe-based superconductors, the FeSe 1−x Te x family of compounds [1-4] is of particular interest. First, it has the simplest PbO structure (space group P 4/nmm) with Se (or Te) atoms forming distorted tetrahedra around Fe (see Fig. 1(a)) similar to the structure of FeAs planes in the families of FeAs-based high T c superconductors [5]. Second, the internal parameters can be systematically tuned by the substitution of Se by Te [6][7][8], which provides us a platform for in-depth study of possible superconducting mechanisms and topological characters. Thirdly, superconductivity has been observed for a wide range of composition x [2-4], and the transition temperature T c can be further enhanced by pressure [9][10][11]. More recently, superconductivity with T c higher than 77 K was suggested for single unit cell FeSe films [12] epitaxially grown on SrTiO 3 substrates.Despite these interesting properties though, the particularities of the system have still not been fully explored. Earlier studies, both theoretical and experimental, suggest the similarity of the electronic structures of the Fe chalcogenides (FeSe, FeTe) [13][14][15] and the FeAsbased [16][17][18] superconductors. Indeed, the low-energy physics around the Fermi level is dominated by the Fe-3d states, and the morphology of the Fermi surfaces is similar. On the other hand, a surprisingly stable (no splitting under external magnetic field) zero-energy bound state (ZBS) at randomly distributed interstitial excess Fe sites was observed in very recent scanning tunneling microscopy (STM) measurements on the surface of superconducting Fe(Te,Se) [19], suggesting possible topological feature of its electronic structure. Obviously, the * * these authors contributed equally to this work. 5p orbitals of Te are more extended and have stronger spin-orbit coupling (SOC) than the 4p orbitals of Se. The consequences of Te substitution, particularly for the bulk topological character of FeSe 1−x Te x , have been largely ignored in the literature and will be the main purpose of the present paper. Based on first-principles calculations combined with angle resolved photoemission spectroscopy (ARPES) measurements, here we report that the electronic structure of FeSe 0.5 Te 0.5 is topologically non-trivial, in sharp contrast to its end member FeSe. The topological properties of FeSe 0.5 Te 0.5 can be characterized ...

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“…3(h)). As the d xy band heavily renormalizes compared to the d xz /d yz bands, it is shallower and hardly resolved with weaker intensity [28]. In Cut#1 (Fig.…”

Section: (D)mentioning

confidence: 99%

Topological nature of theFeSe0.5Te0.5superconductor

et al. 2015

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“…in KFe 2 As 2 [40]. As the Coulomb repulsion strength grows, this has been suggested to eventually result in an orbital-selective Mott transition 41 , observed in alkaline iron selenides 42,43 .…”

Section: Introductionmentioning

confidence: 99%

Ising-nematic order in the bilinear-biquadratic model for the iron pnictides

Ergueta

Nevidomskyy

2015

Phys. Rev. B

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Motivated by the recent inelastic neutron scattering (INS) measurements in the iron pnictides which show a strong anisotropy of spin excitations in directions perpendicular and parallel to the ordering wave-vector even above the magnetic transition temperature TN , we study the frustrated Heisenberg model with a biquadratic spin-spin exchange interaction. Using the Dyson-Maleev (DM) representation, which proves appropriate for all temperature regimes, we find that the spin-spin dynamical structure factors are in excellent agreement with experiment, exhibiting breaking of the C4 symmetry even into the paramagnetic region TN < T < Tσ which we refer to as the Ising-nematic phase. In addition to the Heisenberg spin interaction, we include the biquadratic coupling −K(Si · Sj) 2 and study its effect on the dynamical temperature range Tσ − TN of the Isingnematic phase. We find that this range reduces dramatically when even small values of the interlayer exchange Jc and biquadratic coupling K are included. To supplement our analysis, we benchmark the results obtained using full decoupling in the DM method against those from different non-linear spin-wave theories, including the recently developed generalized spin-wave theory (GSWT), and find good qualitative agreement among the different theoretical approaches as well as experiment for both the spin-wave dispersions and the dynamical structure factors.

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“…To get a unified understanding on the correlation effects in Fe-based superconductors, it is crucial to experimentally explore the orbital selective Mott phase and to resolve its characteristics in the electronic structure. [20,21]. Nevertheless, in these materials, the d xy bands are rather weak or nearly degenerate with other bands near the Fermi energy (E F ), which complicates the analysis on the spectral weight evolution of different orbitals.…”

Section: Introductionmentioning

confidence: 99%

“…Nevertheless, in these materials, the d xy bands are rather weak or nearly degenerate with other bands near the Fermi energy (E F ), which complicates the analysis on the spectral weight evolution of different orbitals. The previous analysis was based on the temperature dependent evolution in the energy distribution curves (EDCs), where the spectral weight of d xy bands diminishes at high temperatures, which cannot be explained by the thermal broadening effect [20,21]. However, anomalous temperature dependent evolution beyond thermal broadening is common in the EDCs of strongly correlated systems [22], which would interfere the temperature dependence of an individual band.…”

Section: Introductionmentioning

confidence: 99%

Temperature-induced orbital selective localization and coherent-incoherent crossover in single-layerFeSe/Nb:BaTiO3/KTaO3

Huang

et al. 2016

Phys. Rev. B

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Iron chalcogenide superconductors are multi-band systems with strong electron correlations. Here we use angle-resolved photoemission spectroscopy to study band dependent correlation effects in single-layer FeSe/Nb:BaTiO 3 /KTaO 3 , a new iron chalcogenide superconductor with non-degenerate electron pockets and interface-enhanced superconductivity. The non-degeneracy of the electron bands helps to resolve the temperature dependent evolution of different bands. With increasing temperature, the single layer FeSe undergoes a band-selective localization, in which the coherent spectral weight of one electron band is completely depleted while that of the other one remains finite. In addition, the spectral weight of the incoherent background is enhanced with increasing temperature, indicating a coherent-incoherent crossover. Signatures of polaronic behavior are observed, suggesting electron-boson interactions. These phenomena help to construct a more complete picture of electron correlations in the FeSe family.

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Atomic structure of Al-GaAs(110) interfaces

Cited by 33 publications

References 33 publications

Topological nature of theFeSe0.5Te0.5superconductor

Topological nature of theFeSe0.5Te0.5superconductor

Ising-nematic order in the bilinear-biquadratic model for the iron pnictides

Temperature-induced orbital selective localization and coherent-incoherent crossover in single-layerFeSe/Nb:BaTiO3/KTaO3

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