Quantum monte carlo simulation of FeAs-based superconductors

Kashurnikov, V. A.; Krasavin, А. V.

doi:10.1134/s0021364013060088

Cited by 15 publications

(18 citation statements)

References 17 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…According to our studies [11,13], the exchange term is important for the correct description of the correlation properties of the system and the manifestation of a certain type of pairing symmetry. At the same time,…”

Section: The Modelmentioning

confidence: 99%

See 1 more Smart Citation

Momentum distribution and non-Fermi-liquid behavior in low-doped two-orbital model: Finite-size cluster quantum Monte Carlo approach

2016

View full text Add to dashboard Cite

The two-dimensional two-orbital Hubbard model is studied with the use of finite-size cluster worldline quantum Monte Carlo algorithm. This model is widely used for simulation of the band structure of FeAs clusters, which are structure elements of Fe-based high-temperature superconductors. The choice of a special basis set of hyper-sites allowed to take into account four-fermion operator terms and to overcome partly the sign problem. Spectral functions and the density of states for various parameters of the model are obtained in the undoped and low-doped regimes. The correlated distortion of the spectral density with the change of doping is observed, and the applicability of the "hard-band" approximation in the doped regime is demonstrated. Profiles of the momentum distribution are obtained for the first Brillouin zone; they have pronounced jump near the Fermi level, which decreases with the growth of the strength of the interaction. The invariance of the Fermi surface with respect to the strength of the interaction is testified. Nesting is found in the case of electron and hole doping. Fermi-liquid parameters of the model are derived. Z-factor grows sharply with the increasing the level of doping, and monotonously decreases with the growth of the strength of the interaction. Moreover, electron-hole doping asymmetry of the Z-factor is revealed. The non-Fermi liquid behaviour and the deviation from Luttinger theorem are observed.

show abstract

Section: The Modelmentioning

confidence: 99%

“…Our previous studies for FeAs clusters of size from 3 × 3 to 10 × 10 have shown the possibility of effective A 1g -pairing [11,13,14]. Note, that all calculations were performed within the limits of the full two-orbital model.…”

Section: Introductionmentioning

confidence: 99%

Momentum distribution and non-Fermi-liquid behavior in low-doped two-orbital model: Finite-size cluster quantum Monte Carlo approach

2016

View full text Add to dashboard Cite

show abstract

“…The quantum continuous time world line Monte Carlo (MC) algorithm (CTWLalgorithm) [12] was used to simulate the full two-orbital model [13,14].…”

Section: Introductionmentioning

confidence: 99%

Band structure and density of states in FeAs-based superconductors

Kashurnikov

Krasavin

2015

J. Phys.: Conf. Ser.

View full text Add to dashboard Cite

Abstract. The generalized quantum Monte Carlo algorithm was used to obtain one-particle excitation spectrum and electron density of states for two-dimensional FeAs-clusters modeling iron-based superconductors within the limits of the full two-orbital model. The calculations were performed for clusters with sizes up to 10×10 FeAs-cells. The excitation spectra were reconstructed from Matsubara Green's function. The spectral density of states and the total density of states near the Fermi level were obtained. The data are in accordance with known experimental results. The influence of the cluster size, temperature, and the interaction strength on the density of states was analysed. IntroductionIron-based high-temperature superconductors (HTSC) [1][2][3] are among the most interesting objects of research in the physics of superconductivity nowadays. As well as copper-based HTSC, these compounds have a layered structure. However, due to the features of the multi-gap band structure they have a complex phase diagram which includes antiferromagnetic, structural, and superconducting phase transitions [4][5][6][7][8][9].Iron-based HTSC due to their pronounced anisotropy can be successfully described within the limits of two-dimensional tight-binding models. One of the most appropriate models for this purpose is the two-orbital model [10,11] which is a typical multi-band generalized Hubbard model. The lack of expansion parameters for analytical approximations, and the presence of strong Coulomb correlations assume the use of exact numerical quantum methods for the study of iron-based HTSC.The present work continues the study of electronic correlations in big FeAs-clusters and focuses on the calculation of the spectrum of elementary excitations which determines the Fermi surface and the density of states. The quantum continuous time world line Monte Carlo (MC) algorithm (CTWLalgorithm) [12] was used to simulate the full two-orbital model [13,14].According to experimental data and calculations based on DMFT and LDA techniques [4,6,[15][16][17], it is the quasiparticle spectrum which forms a complex multi-gap band structure. Furthermore, the density of states near the Fermi level is almost entirely determined by d-states of iron atoms, which gives reason to believe that all the phenomena associated with conducting and superconducting properties of these compounds are played on the FeAs-plane.The quantum algorithm developed in [13] allows one to calculate the Matsubara Green's function and to obtain the quasiparticle spectrum and its dependence on the system size and interaction parameters. The first data are presented on the excitation spectrum in the framework of the full twoorbital model for clusters with sizes up to 10×10 FeAs cells.

show abstract

“…Preliminary studies of electron correlations in large FeAs clusters developed earlier by the authors in a series of papers [11][12][13][14][15] with the use of quantum trajectory Monte Carlo algorithm that does not use the Wick's expansion and thus asymptotically exact, allowed to obtain results correlated with other experimental and calculated data. Calculations for FeAs clusters with the number of cells from 3 × 3 to 10 × 10 showed the presence of multi-band structure of the spectrum of the charge carriers; calculations of pair correlation functions demonstrated the possibility of effective attraction of carriers with A 1g symmetry [11][12][13]. The present work is devoted to the analysis of the spectrum of elementary excitations, which determines the Fermi surface and the density of states.…”

mentioning

confidence: 99%

“…The minimalistic two-orbital model gives the opportunity to investigate it with a generalized quantum trajectory Monte Carlo algorithm; the coding of basis states and other features of the calculation of correlation functions are reported in detail in [11][12][13]. The parameters of H kin parameters in (1) were taken from [7]:…”

mentioning

confidence: 99%

Calculation of Density of States for FeAs-based Superconductors

Kashurnikov¹,

Krasavin²,

Zhumagulov³

2017

J. Sib. Fed. Univ., Math. phys.

View full text Add to dashboard Cite

The spectral and the total density of states were calculated for two-dimensional FeAs-clusters The discovery of high-temperature superconductors (HTSC) based on iron [1] was a new incentive to determination of nature of superconductivity in complex compounds with a layered structure. Compared to copper-based HTSC, the iron-based compounds have a more complex phase diagram, which includes antiferromagnetic, structural, and superconducting phase transitions [2,3]. The key subject of the research now is the role of electron correlations in iron-based HTSC, which, generally, are crucial in the formation of physical properties of systems containing transition elements [4].As well as copper-based HTSC, iron-based high-temperature superconductors are characterized by strongly expressed anisotropy, and have a structure, which consists of closely spaced atomic planes of Fe and As (for pnyctides). Estimates and ARPES experiment show that the quasiparticle spectrum forms a complex multi-band structure with hole and electron pockets in the Brillouin zone; the density of states near the Fermi level is the same for most of 122-and 1111-type compounds, and weakly depends on the interaction parameters [5].The description of physical properties of these compounds within the limits of a twodimensional tight-binding model such as the two [6,7], three [8,9] and five-orbital model [9,10], which are typical generalized Hubbard models, do not provide the correct analysis in various approximations, including the mean-field approximation. The complexity of these models leads *

show abstract

Quantum monte carlo simulation of FeAs-based superconductors

Cited by 15 publications

References 17 publications

Momentum distribution and non-Fermi-liquid behavior in low-doped two-orbital model: Finite-size cluster quantum Monte Carlo approach

Momentum distribution and non-Fermi-liquid behavior in low-doped two-orbital model: Finite-size cluster quantum Monte Carlo approach

Band structure and density of states in FeAs-based superconductors

Calculation of Density of States for FeAs-based Superconductors

Contact Info

Product

Resources

About