Observation of a remarkable reduction of correlation effects in BaCr
            <sub>2</sub>
            As
            <sub>2</sub>
            by ARPES

Nayak, J.; Filsinger, Kai Alexander; Fecher, Gerhard H.; Chadov, Stanislav; Minář, J.; Rienks, E. D. L.; Büchner, B.; Parkin, Stuart; Fink, J.; Felser, Claudia

doi:10.1073/pnas.1702234114

Cited by 19 publications

(18 citation statements)

References 46 publications

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“…Regions with a linear increase of the scattering rates as a function of energy have been detected in other FeSCs and related compounds and were discussed in previous publications [43,[47][48][49] in terms of momentum and not orbital dependent strong correlation effects and the proximity to the Planckian limit [50].…”

Section: Data Evaluation and Electronic Structure Calculationsmentioning

confidence: 65%

Evidence of hot and cold spots on the Fermi surface of LiFeAs

et al. 2019

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Angle-resolved photoemission spectroscopy (ARPES) is used to study the energy and momentum dependence of the inelastic scattering rates and the mass renormalization of charge carriers in LiFeAs at several high symmetry points in the Brillouin zone. A strong and linear-in-energy scattering rate is observed for sections of the Fermi surface having predominantly Fe 3d xy/yz orbital character on the inner hole and on electron pockets. We assign them to hot spots with marginal Fermi liquid character inducing high antiferromagnetic and pairing susceptibilities. The outer hole pocket, with Fe 3dxy orbital character, has a reduced but still linear in energy scattering rate. Finally, we assign sections on the middle hole pockets with Fe 3dxz,yz orbital character and on the electron pockets with Fe 3dxy orbital character to cold spots because there we observe a quadratic-in-energy scattering rate with Fermi-liquid behavior. These cold spots prevail the transport properties. Our results indicate a strong momentum dependence of the scattering rates. We also have indications that the scattering rates in correlated systems are fundamentally different from those in non-correlated materials because in the former the Pauli principle is not operative. We compare our results for the scattering rates with combined density functional plus dynamical mean-field theory calculations. The work provides a generic microscopic understanding of macroscopic properties of multiorbital unconventional superconductors. arXiv:1807.11220v2 [cond-mat.supr-con]

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Section: Data Evaluation and Electronic Structure Calculationsmentioning

confidence: 65%

Evidence of hot and cold spots on the Fermi surface of LiFeAs

et al. 2019

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“…Insets: Cp/T versus T 2 for the three crystals #2, #3, and Sn-flux-grown #6 EuCo 1.94(2) As2. The data do not follow the behavior expected from Eq (22)…”

mentioning

confidence: 59%

“…An important family of these materials consists of doped and undoped compounds AFe 2 As 2 (A = Ca, Sr, Ba, Eu) with the body-centered tetragonal ThCr 2 Si 2 structure with space group I4/mmm (122-type compounds). Searches for novel physical properties in various 122-type compounds with other transition metals replacing Fe have been carried out, such as for Mn [10][11][12][13][14][15][16][17][18][19] and Cr [20][21][22][23][24][25][26][27].…”

Section: Introductionmentioning

confidence: 99%

Enhanced moments of Eu in single crystals of the metallic helical antiferromagnetEuCo2−yAs2

et al. 2018

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The compound EuCo2−yAs2 with the tetragonal ThCr2Si2 structure is known to contain Eu +2 ions with spin S = 7/2 that order below a temperature TN ≈ 47 K into an antiferromagnetic (AFM) proper helical structure with the ordered moments aligned in the tetragonal ab plane, perpendicular to the helix axis along the c axis, with no contribution from the Co atoms. Here we carry out a detailed investigation of the properties of single crystals. We consistently find about 5% vacancies on the Co site from energy-dispersive x-ray analysis and x-ray diffraction refinements. Enhanced ordered and effective moments of the Eu spins are found in most of our crystals. Electronic structure calculations indicate that the enhanced moments arise from polarization of the d bands, as occurs in ferromagnetic Gd metal. Electrical resistivity measurements indicate metallic behavior. The lowfield in-plane magnetic susceptibilities χ ab (T < TN) for several crystals are reported that are fitted well by unified molecular field theory (MFT), and the Eu-Eu exchange interactions Jij are extracted from the fits. High-field magnetization M data for magnetic fields H ab reveal what appears to be a first-order spin-flop transition followed at higher field by a second-order metamagnetic transition of unknown origin, and then by another second-order transition to the paramagnetic (PM) state. For H c, the magnetization shows only a second-order transition from the canted AFM to the PM state, as expected. The critical fields for the AFM to PM transition are in approximate agreement with the predictions of MFT. Heat capacity Cp measurements in zero and high H are reported. Phase diagrams for H c and H ab versus T are constructed from the high-field M (H, T ) and Cp(H, T ) measurements. The magnetic part Cmag(T, H = 0) of Cp(T, H = 0) is extracted and is fitted rather well below TN by MFT, although dynamic short-range AFM order is apparent in Cmag(T ) up to about 70 K, where the molar entropy attains its high-T limit of R ln 8.

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“…The existence of well-defined quasiparticles suggests a Hund-induced orbital decoupling phenomenon [45] between Mott localized and itinerant components of the many-particle electronic fluid at high pressures. The interplay between local electronic correlations and bandwidth broadening in pressurized BaFe 2 Se 3 yields a promising and practical route to access orbital-resolved quasiparticles [45] and scattering rates [56] of Hund's metals, but this prediction for BaFe 2 Se 3 remains to be seen in future studies. personal Heisenberg grant.…”

Section: Discussionmentioning

confidence: 99%

Pressure-induced orbital-selective metal from the Mott insulator BaFe2Se3

Craco

Leoni

2020

Phys. Rev. B

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A general understanding of the mechanism underlying the pressure-induced Mott insulator-metal transition in strongly correlated materials is still lacking. Here we explore the pressure-induced electronic reconstruction in BaFe 2 Se 3 , a potential two-leg ladder system for unconventional (non-BCS) superconductivity. We stress the importance of multiorbital Coulomb interactions in concert with first-principles band-structure calculations for a consistent understanding of its intrinsic Mott-Hubbard insulating state both at ambient and under pressure. We elucidate the nature of pressure-induced insulator-metal transition seen in experiment, showing that it is driven by bandwidth broadening under pressure. We reveal an orbital-selective electronic state where Mott localized and itinerant electrons coexist in compressed BaFe 2 Se 3 , which incorporates orbital-resolved scattering rates and renormalization factors hidden in the normal state at high pressures.

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Observation of a remarkable reduction of correlation effects in BaCr ₂ As ₂ by ARPES

Cited by 19 publications

References 46 publications

Evidence of hot and cold spots on the Fermi surface of LiFeAs

Evidence of hot and cold spots on the Fermi surface of LiFeAs

Enhanced moments of Eu in single crystals of the metallic helical antiferromagnetEuCo2−yAs2

Pressure-induced orbital-selective metal from the Mott insulator BaFe2Se3

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Observation of a remarkable reduction of correlation effects in BaCr 2 As 2 by ARPES

Cited by 19 publications

References 46 publications

Evidence of hot and cold spots on the Fermi surface of LiFeAs

Evidence of hot and cold spots on the Fermi surface of LiFeAs

Enhanced moments of Eu in single crystals of the metallic helical antiferromagnetEuCo2−yAs2

Pressure-induced orbital-selective metal from the Mott insulator BaFe2Se3

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Observation of a remarkable reduction of correlation effects in BaCr ₂ As ₂ by ARPES