scholarly journals Non-local dxy nematicity and the missing electron pocket in FeSe

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Luke C. Rhodes ◽  
Jakob Böker ◽  
Marvin A. Müller ◽  
Matthias Eschrig ◽  
Ilya M. Eremin
Keyword(s):  
Experimental Data ◽  
Superconducting Gap ◽  
Momentum Dependence ◽  
Natural Explanation ◽  
Iron Based Superconductors ◽  
Nematic Ordering ◽  
Lifshitz Transition ◽  
Non Local ◽  
Iron Based ◽  
Electron Pocket

AbstractThe origin of spontaneous electronic nematic ordering provides important information for understanding iron-based superconductors. Here, we analyze a scenario where the dxy orbital strongly contributes to nematic ordering in FeSe. We show that the addition of dxy nematicity to a pure dxz/dyz order provides a natural explanation for the unusual Fermi surface and correctly reproduces the strongly anisotropic momentum dependence of the superconducting gap. We predict a Lifshitz transition of an electron pocket mediated by temperature and sulfur doping, whose signatures we discuss by analysing available experimental data. We present the variation of momentum dependence of the superconducting gap upon suppression of nematicity. Our quantitatively accurate model yields the transition from tetragonal to nematic FeSe and the FeSe1−xSx series, and puts strong constraints on possible nematic mechanisms.

scholarly journals Momentum Dependence of the Nematic Order Parameter in Iron-Based Superconductors

2019 ◽  
Vol 123 (6) ◽  
Author(s):  
H. Pfau ◽  
S. D. Chen ◽  
M. Yi ◽  
M. Hashimoto ◽  
C. R. Rotundu ◽  
...  
Keyword(s):  
Order Parameter ◽  
Momentum Dependence ◽  
Iron Based Superconductors ◽  
Nematic Order ◽  
Iron Based

scholarly journals Glide-Plane Symmetry and Superconducting Gap Structure of Iron-Based Superconductors

2015 ◽  
Vol 114 (10) ◽  
Author(s):  
Y. Wang ◽  
T. Berlijn ◽  
P. J. Hirschfeld ◽  
D. J. Scalapino ◽  
T. A. Maier
Keyword(s):  
Superconducting Gap ◽  
Plane Symmetry ◽  
Iron Based Superconductors ◽  
Iron Based ◽  
Gap Structure

THERMODYNAMIC PROPERTIES OF IRON-BASED SUPERCONDUCTOR

2011 ◽  
Vol 25 (31) ◽  
pp. 2363-2370
Author(s):  
FANGYING LIANG
Keyword(s):  
Experimental Data ◽  
Thermal Properties ◽  
Thermodynamic Properties ◽  
Time Dependent ◽  
Recent Experimental Data ◽  
Layer Model ◽  
Ginzburg Landau ◽  
Iron Based Superconductors ◽  
Landau Model ◽  
Iron Based

We consider a modified time-dependent Ginzburg-Landau model (TDGL) and layer model of Lawrence–Doniach to study the thermal properties in iron-based superconductors. We try to calculate the specific heat, and obtain some formulae. The expressions will be useful in the discussions of some of the most recent experimental data.

scholarly journals The Role of Orbital Nesting in the Superconductivity of Iron-Based Superconductors

2021 ◽  
Vol 6 (3) ◽  
pp. 34
Author(s):  
Raquel Fernández-Martín ◽  
María J. Calderón ◽  
Laura Fanfarillo ◽  
Belén Valenzuela
Keyword(s):  
Low Energy ◽  
Gap Functions ◽  
Momentum Dependence ◽  
Iron Based Superconductors ◽  
Spin Excitations ◽  
The Common ◽  
Iron Based ◽  
Orbital Character ◽  
Key Parameter

We analyze the magnetic excitations and the spin-mediated superconductivity in iron-based superconductors within a low energy model that operates in the band basis, but fully incorporates the orbital character of the spin excitations. We show how the orbital selectivity, encoded in our low energy description, simplifies substantially the analysis and allows for analytical treatments, while retaining all the main features of both spin excitations and gap functions computed using multiorbital models. Importantly, our analysis unveils the orbital matching between the hole and electron pockets as the key parameter to determine the momentum dependence and the hierarchy of the superconducting gaps, instead of the Fermi surface matching, as in the common nesting scenario.

scholarly journals Pressure-dependent topological superconductivity on the surface of FeTe0.5Se0.5

2022 ◽  
Author(s):  
Chih-Kai Yang ◽  
Chi-Hsuan Lee
Keyword(s):  
Exchange Interaction ◽  
Density Functional ◽  
Applied Pressure ◽  
Bcs Theory ◽  
Superconducting Gap ◽  
Cooper Pairs ◽  
S Wave ◽  
Iron Based Superconductors ◽  
Iron Based ◽  
Critical Temperature Tc

Abstract FeTe1-xSex is a family of iron-based superconductors with its critical temperature (Tc) dependent on the composition of Se. A well-known Tc is 14.5 K for x = 0.45, which exhibits an s-wave superconducting gap between the topological superconducting surfaces states. Exchange interaction between the electrons has been proposed as the mechanism behind the formation of Cooper pairs for the sample of FeTe0.5Se0.5. In this article we provide further proof that exchange interaction, and hence the associated Tc, depends on the applied pressure on FeTe0.5Se0.5. Using density functional calculations for electrons and phonons and the Bardeen-Cooper-Schrieffer (BCS) theory for superconductivity, we found that Tc and superconducting gap for FeTe0.5Se0.5 soars under increasing compression, consistent with the results of experiment.

scholarly journals Revealing the intrinsic superconducting gap anisotropy in surface-neutralized BaFe2(As0.7P0.3)2

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Ziming Xin ◽  
Yudi Wang ◽  
Cong Cai ◽  
Zhengguo Wang ◽  
Lei Chen ◽  
...  
Keyword(s):  
Alkaline Earth ◽  
Theoretical Models ◽  
Photoemission Spectroscopy ◽  
Superconducting Gap ◽  
Iron Based Superconductors ◽  
Future Studies ◽  
Angle Resolved Photoemission Spectroscopy ◽  
Gap Anisotropy ◽  
Iron Based ◽  
Potassium Deposition

AbstractAlkaline-earth iron arsenide (122) is one of the most studied families of iron-based superconductors, especially for angle-resolved photoemission spectroscopy. While extensive photoemission results have been obtained, the surface complexity of 122 caused by its charge-non-neutral surface is rarely considered. Here, we show that the surface of 122 can be neutralized by potassium deposition. In potassium-coated BaFe2(As0.7P0.3)2, the surface-induced spectral broadening is strongly suppressed, and hence the coherent spectra that reflect the intrinsic bulk electronic state recover. This enables the measuring of superconducting gap with unpreceded precision. The result shows the existence of two pairing channels. While the gap anisotropy on the outer hole/electron pockets can be well fitted using an s± gap function, the gap anisotropy on the inner hole/electron shows a clear deviation. Our results provide quantitative constraints for refining theoretical models and also demonstrate an experimental method for revealing the intrinsic electronic properties of 122 in future studies.

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