Investigation of correlation effects in FeSe and FeTe by LDA+U method

Lohani, Himanshu; Mishra, Pramita; Sekhar, B.R.

doi:10.1016/j.physc.2015.03.001

Cited by 13 publications

(15 citation statements)

References 45 publications

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“…The calculated band structure along the Γ-Z line suggests that, because the dispersion of the bands is linear in k z -direction this system can be treated as a two-dimensional one. This result agrees qualitatively with the previous calculations [67,[123][124][125][126][127][128][129][130]. Similarly like in CeCoIn 5 , in the absence of the external magnetic field c e D ( ) q for FeSe clearly shows a tendency of the system to realize the homogeneous superconductivity of the BCS-type in each band.…”

Section: Iron Based Superconductor: Fesesupporting

confidence: 91%

Theab initiostudy of unconventional superconductivity in CeCoIn₅and FeSe

et al. 2017

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The electronic structure and shape of the Fermi surface are known to be of fundamental importance for the superconducting instability in real materials. We demonstrate that such an instability may be explored by static Cooper pair susceptibility renormalized by pairing interaction and present an efficient method of its evaluation using Wannier orbitals derived from ab initio calculation. As an example, this approach is used to search for an unconventional superconducting phase of the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) type in a heavy-fermion compound CeCoIn 5 and an iron-based superconductor FeSe. The results suggest that the FFLO superconducting phase occurs at finite magnetic field in both materials. P 2 orb 2 [9], which describes the ratio of the critical magnetic fields at zero temperature given only OPEN ACCESS

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Section: Iron Based Superconductor: Fesesupporting

confidence: 91%

Theab initiostudy of unconventional superconductivity in CeCoIn₅and FeSe

et al. 2017

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“…The Fermi surface (FS) and low-energy bandstructures of FeSe have extensively been investigated [14,[26][27][28][29][30][31][32][33][34][35][36][37][38], where the multiorbital compensated metal with Fe-d orbitals is confirmed [6,7]. In normal (nonnematic) state, two hole FSs (2h-FSs) around Γ and two electron FSs (2e-FSs) around M have commonly been reported but their size is extremely small only occupied 2-3 % in the Brillouin Zone (BZ).…”

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confidence: 99%

Multipolar nematic state of nonmagnetic FeSe based on the DFT+$U$

Yamada,

Tohyama

2021

Preprint

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Clarifying the origin of nematic state in FeSe is one of urgent problems in the field of iron-based superconductivity. Motivated by the discovery of a nematic solution in the density-functional theory implemented by on-site Coulomb interaction (DFT+U ) [X. Long et al., npj Quantum Mater. 5, 50 (2020)], we reexamine the U dependence of electronic states in the nonmagnetic normal state of FeSe and perform full multipolar analyses for the nematic state. We find that with increasing U the normal state experiences a topological change of the Fermi surfaces before the emergence of a nematic ground state. The resulting nematic ground state is a multipolar state having both antiferro-hexadecapoles in the E-representation and ferro-multipoles in the B2-representation on each Fe site. Cooperative coupling between the E and B2 multipoles in local coordinate with the D 2d point group will play an important role in the formation of the dxz, dyz orbital-splitting nematic state not only in FeSe but also in other iron pnictides.

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“…These results imply that the optical conductivity for FeSe cannot be described rightly by the standard Durde formula which gives that σ 1 (ω) should decrease with increasing ω and σ 2 (ω) should always be positive. In superconducting phase (T < 10 K), the optical conductivity in NIR bandwidth is mainly induced by the correlation effect of FeSe superconductor in the presence of the Hund's coupling of Fe 3d orbitals [33], [34]. From σ 2 (ω) shown in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…It is known that the upper Se-Fe-Se angle or two Fe-Fe distances can be altered across T s ∼90 K [35], which mainly affects the Fe 3d orbital [16] and results in a tetragonal to orthorhombic structural phase transition [35]. Therefore, in different structural phases the electronic mobility or dc conductivity should be different in FeSe where the Hund's coupling between itinerant electrons and localized electrons plays an important role in determining the electronic and optical properties of FeSe [33].…”

Section: Resultsmentioning

confidence: 99%

Near-Infrared Reflectivity of Superconducting FeSe Thin Films

Zhang

Feng

et al. 2019

IEEE Photonics J.

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We present an investigation on the intrinsic optical properties of superconducting FeSe thin films deposited on CaF 2 substrates. It is found that the samples respond strongly to the near-infrared (NIR) irradiation in different temperature regimes. Thus, we are able to measure the optical reflectivity of the in-plane (ab-plane) thin films from room temperature to 5 K. A critical behavior near the superconducting transition temperature (T c ∼10 K) can be observed optically in the temperature-dependent reflectivity spectrum. We carry out the Kramers-Kronig analysis of the experimental data and discuss the basic optical properties of superconducting FeSe thin films in different structural phases above and below the transition temperature T s ∼100 K. By fitting experimental data with the Drude-Smith and Drude-Lorentz formulas, we obtain the key sample parameters such as the electronic relaxation time and dc conductivity. The interesting and important findings obtained from this study not only shed new light on the pairing mechanism in FeSe but also demonstrate that the NIR reflection experiment is a powerful and convenient optical technique for contactless characterization and investigation of superconducting thin film materials.

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Investigation of correlation effects in FeSe and FeTe by LDA+U method

Cited by 13 publications

References 45 publications

Theab initiostudy of unconventional superconductivity in CeCoIn₅and FeSe

Theab initiostudy of unconventional superconductivity in CeCoIn₅and FeSe

Multipolar nematic state of nonmagnetic FeSe based on the DFT+$U$

Near-Infrared Reflectivity of Superconducting FeSe Thin Films

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Investigation of correlation effects in FeSe and FeTe by LDA+U method

Cited by 13 publications

References 45 publications

Theab initiostudy of unconventional superconductivity in CeCoIn5and FeSe

Theab initiostudy of unconventional superconductivity in CeCoIn5and FeSe

Multipolar nematic state of nonmagnetic FeSe based on the DFT+$U$

Near-Infrared Reflectivity of Superconducting FeSe Thin Films

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Product

Resources

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Theab initiostudy of unconventional superconductivity in CeCoIn₅and FeSe

Theab initiostudy of unconventional superconductivity in CeCoIn₅and FeSe