Effect of electron correlations on the electronic structure and phase stability of FeSe upon lattice expansion

Skornyakov, S. L.; Анисимов, В. И.; Vollhardt, D.; Leonov, I.

doi:10.1103/physrevb.96.035137

Cited by 38 publications

(30 citation statements)

References 100 publications

(56 reference statements)

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“…While it is proposed that the two d xz/yz bands can split due to spin-orbit coupling 23 or orthorhombic distortions 24 , it is striking that the d xy band appears to be pushed down by as much as 50 meV compared to reported DFT calculations. Reported DFT+DMFT calculations seem to also fail to capture the strong pocket shrinkage and do not reproduce the suppression of the d xy band below the Fermi level [25][26][27] . At lower temperatures, the FeSe system becomes strongly nematic without long range magnetism, an effect that was not found in any first principles calculation until quite recently 28 with a combination of LDA+U and an enlarged unit cell scheme, whose generality is currently unclear.…”

Section: Introductionmentioning

confidence: 98%

Non-local correlations in Iron Pnictides and Chalcogenides

Bhattacharyya,

Björnson,

Zantout

et al. 2020

Preprint

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Deviations of low-energy electronic structure of iron-based superconductors from density functional theory predictions have been parametrized in terms of band-and orbital-dependent mass renormalizations and energy shifts. The former have typically been described in terms of a local self-energy within the framework of dynamical mean field theory, while the latter appears to require non-local effects due to interband scattering. By calculating the renormalized bandstructure in both random phase approximation (RPA) and the two-particle self-consistent approximation (TPSC), we show that correlations in pnictide systems like LaFeAsO and LiFeAs can be described rather well by a non-local self-energy. In particular, Fermi pocket shrinkage as seen in experiment occurs due to repulsive interband finite-energy scattering. For the canonical iron chalcogenide system FeSe in its bulk tetragonal phase, the situation is however more complex since even including momentum-dependent band renormalizations cannot explain experimental findings. We propose that the long-range Coulomb interaction may play an important role in band-structure renormalization in FeSe. We further compare our evaluations of non-local quasiparticle scattering lifetime within RPA and TPSC with experimental data for LiFeAs.

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Section: Introductionmentioning

confidence: 98%

Non-local correlations in Iron Pnictides and Chalcogenides

Bhattacharyya,

Björnson,

Zantout

et al. 2020

Preprint

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“…Our results for the evolution of magnetic correlations and possible magnetic instabilities of (Nd,Sr)NiO 2 upon Sr doping are analyzed by calculating the momentum-resolved static susceptibility in the particle-hole bubble approximation, with the interacting lattice Green's function evaluated within DFT+DMFT (see, e.g., Refs. [15,55,56,70,71]). Using the DFT and DFT+DMFT methods we compute the electronic structure of the ferromagnetic (FM), Néel (111), C-type (110), single-stripe (100), (001), and staggered dimer (11 1 2 ) AFM states of (Nd,Sr)NiO 2 .…”

Section: Computational Detailsmentioning

confidence: 99%

“…DFT+DMFT has been proven to be among the most advanced theoretical methods for studying the electronic properties of strongly correlated materials, such as correlated transition metal oxides, heavy-fermions, and Fe-based superconductors, e.g., to study the phenomena of a Mott transition, collapse of local moments, large orbital-dependent renormalizations, etc. [48][49][50][51][52][53][54][55][56][57][58][59][60]. We use this advanced computational method to explore the effects of electronic correlations and Sr doping on the electronic structure, magnetic correlations, and exchange couplings of the unstrained (Nd,Sr)NiO 2 .…”

Section: Introductionmentioning

confidence: 99%

Effect of epitaxial strain on the electronic structure and magnetic correlations in infinite-layer (Nd,Sr)NiO$_2$

Leonov¹,

Savrasov²

2020

Preprint

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We present a theoretical study of the effect of electron-electron interactions and Sr doping on the electronic structure of infinite-layer (Nd,Sr)NiO2 using the density functional+dynamical mean-field theory approach. In particular, we explore the impact of epitaxial compressive strain that experience (Nd,Sr)NiO2 films on the electronic properties, magnetic correlations, and exchange couplings. Our results reveal the crucial importance of orbital-dependent correlation effects in the Ni 3d shell of Sr-doped NdNiO2. Upon doping with Sr, it undergoes a Lifshitz transition which is accompanied by a reconstruction of magnetic correlations: For Sr x < 0.2 (Nd,Sr)NiO2 adopts the Néel ( 111) antiferromagnetic (AFM) order, while for x > 0.2 the C-type (110) AFM sets in the unstrained (Nd,Sr)NiO2, with a highly frustrated region at x 0.2, all within DFT+DMFT at T = 290 K. Our results for the Néel AFM at Sr x = 0 suggest that AFM NdNiO2 appears at the verge of a Mott-Hubbard transition, providing a plausible explanation for the experimentally observed weakly insulating behavior of NdNiO2 for Sr x < 0.1. We observe that the Lifshitz transition makes a change of the band structure character from electron-to hole-like with Sr x, in agreement with recent experiments. Our results for magnetic couplings demonstrate an unanticipated frustration of the Ni 3d magnetic moments, which suppresses magnetic order near Sr x = 0.2. We find that the effect of frustration is maximal for Sr doping x 0.1 − 0.2 that nearly corresponds to the experimentally observed doping value. We conclude that the in-plane strain adjusts a bandwidth of the Ni x 2 − y 2 band, i.e., controls the effect of electron correlations in the Ni x 2 − y 2 orbitals. It suppresses the static C-type (110) ordering in (Nd,Sr)NiO2 for Sr x > 0.2. Moreover, the in-plane strain affects the character of the Fermi surface of Sr-doped NdNiO2 near the Brillouin zone A point, adjusting the crossover from electron-to hole-like behavior at high Sr x. The electronic structure and magnetic correlations of (Nd,Sr)NiO2 reveal an anomalous sensitivity upon a change of the crystal structure parameters.

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“…Moreover, a double-stripe (π, 0)-type magnetically ordered phase appears upon expansion of the lattice caused by an isoelectronic substation of Se with Te, in FeTe [19]. The (π, π) to (π, 0) crossover in magnetic correlations can be attributed to a Lifshitz transition of the electronic band structure of Fe(Se,Te), accompanied by a remarkable increase of local magnetic moments and an enhancement of electronic compressibility at the transition point [20][21][22]. This behavior was ascribed to, e.g., a correlation-induced shift of the Van Hove singularity associated with the Fe xy and xz/yz orbitals at the Brillouin zone M point across the Fermi level [20][21][22].…”

Section: Introductionmentioning

confidence: 99%

Correlated electronic structure, orbital-dependent correlations, and Lifshitz transition in tetragonal FeS

Skornyakov

Leonov

2019

Phys. Rev. B

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Iron-based binary chalcogenide superconductors FeSe and FeS have attracted much recent attention due to their complex orbital-selective correlations and Cooper pairing, offering the minimal model system holding the key properties to understanding the physics of high-Tc superconductors. Here, using density functional plus dynamical mean-field theory method (DFT+DMFT) with full self-consistency over the charge density, we study the effect of electronic correlations on the electronic structure, magnetic properties, orbital-dependent band renormalizations, and Fermi surface of the tetragonal phase of bulk FeS. We perform a direct structural optimization of the P4/nmm crystal structure of paramagnetic FeS, minimizing the total energy of FeS with respect to the lattice constant a and the internal coordinate zS of atom S. Our results show an anomalous sensitivity of the electronic structure and magnetic properties of FeS to fine details of its crystals structure, e.g., to a small variation of the chalcogen coordinate zS. Upon expansion of the lattice volume (which can be realized, e.g., in FeS1−xSex), we observe a remarkable change of the electronic structure of FeS which is associated with a complete reconstruction of the Fermi surface topology (Lifshitz transition). This behavior is ascribed to a correlation-induced shift of the Van Hove singularity associated with the Fe xy and xz/yz orbitals at the M point across the Fermi level. The Lifshitz phase transition is accompanied by a significant growth of local magnetic moments and emergence of strong orbital-selective correlations. It is seen as a pronounced anomaly ('kink') in the total energies upon expansion of the lattice, associated with a remarkable enhancement of compressibility. This behavior is accompanied by an orbital-dependent formation of local moments, a crossover from itinerant to localized orbital-selective moment behavior of the Fe 3d electrons. While exhibiting weak effective mass enhancement of the Fe 3d states m * /m ∼ 1.3 − 1.4, correlation effects reveal a strong impact on a position of the Van Hove singularity originating from the Fe xz/yz and xy orbitals at the M point, implying a complex interplay between electronic correlations and band structure effects in FeS. Our results suggest a complex interplay between electronic correlations, magnetism, and lattice degrees of freedom in FeS.

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Effect of electron correlations on the electronic structure and phase stability of FeSe upon lattice expansion

Cited by 38 publications

References 100 publications

Non-local correlations in Iron Pnictides and Chalcogenides

Non-local correlations in Iron Pnictides and Chalcogenides

Effect of epitaxial strain on the electronic structure and magnetic correlations in infinite-layer (Nd,Sr)NiO$_2$

Correlated electronic structure, orbital-dependent correlations, and Lifshitz transition in tetragonal FeS

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