| 1. |
- Küspert, Julia, et al.
(författare)
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Pseudogap suppression by competition with superconductivity in La-based cuprates
- 2022
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Ingår i: Physical Review Research. - 2643-1564. ; 4:4
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Tidskriftsartikel (refereegranskat)abstract
- We carried out a comprehensive high-resolution angle-resolved photoemission spectroscopy (ARPES) study of the pseudogap interplay with superconductivity in La-based cuprates. The three systems La2-xSrxCuO4, La1.6-xNd0.4SrxCuO4, and La1.8-xEu0.2SrxCuO4 display slightly different pseudogap critical points in the temperature versus doping phase diagram. We studied the pseudogap evolution into the superconducting state for doping concentrations just below the critical point. In this setting, near optimal doping for superconductivity and in the presence of the weakest possible pseudogap, we uncover how the pseudogap is partially suppressed inside the superconducting state. This conclusion is based on the direct observation of a reduced pseudogap energy scale and re-emergence of spectral weight suppressed by the pseudogap. Altogether these observations suggest that the pseudogap phenomenon in La-based cuprates is in competition with superconductivity for antinodal spectral weight.
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| 2. |
- Horio, M., et al.
(författare)
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Electronic reconstruction forming a C-2-symmetric Dirac semimetal in Ca3Ru2O7
- 2021
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Ingår i: npj Quantum Materials. - : Springer Science and Business Media LLC. - 2397-4648. ; 6:1
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Tidskriftsartikel (refereegranskat)abstract
- Electronic band structures in solids stem from a periodic potential reflecting the structure of either the crystal lattice or electronic order. In the stoichiometric ruthenate Ca3Ru2O7, numerous Fermi surface-sensitive probes indicate a low-temperature electronic reconstruction. Yet, the causality and the reconstructed band structure remain unsolved. Here, we show by angle-resolved photoemission spectroscopy, how in Ca3Ru2O7 a C-2-symmetric massive Dirac semimetal is realized through a Brillouin-zone preserving electronic reconstruction. This Dirac semimetal emerges in a two-stage transition upon cooling. The Dirac point and band velocities are consistent with constraints set by quantum oscillation, thermodynamic, and transport experiments, suggesting that the complete Fermi surface is resolved. The reconstructed structure-incompatible with translational-symmetry-breaking density waves-serves as an important test for band structure calculations of correlated electron systems.
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| 3. |
- Horio, M., et al.
(författare)
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Orbital-selective metal skin induced by alkali-metal-dosing Mott-insulating Ca 2 RuO 4
- 2023
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Ingår i: Communications Physics. - 2399-3650. ; 6:1
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Tidskriftsartikel (refereegranskat)abstract
- Doped Mott insulators are the starting point for interesting physics such as high temperature superconductivity and quantum spin liquids. For multi-band Mott insulators, orbital selective ground states have been envisioned. However, orbital selective metals and Mott insulators have been difficult to realize experimentally. Here we demonstrate by photoemission spectroscopy how Ca2RuO4, upon alkali-metal surface doping, develops a single-band metal skin. Our dynamical mean field theory calculations reveal that homogeneous electron doping of Ca2RuO4 results in a multi-band metal. All together, our results provide evidence for an orbital-selective Mott insulator breakdown, which is unachievable via simple electron doping. Supported by a cluster model and cluster perturbation theory calculations, we demonstrate a type of skin metal-insulator transition induced by surface dopants that orbital-selectively hybridize with the bulk Mott state and in turn produce coherent in-gap states.
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| 4. |
- Horio, M., et al.
(författare)
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Oxide Fermi liquid universality revealed by electron spectroscopy
- 2020
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Ingår i: Physical Review B. - 2469-9969 .- 2469-9950. ; 102:24
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Tidskriftsartikel (refereegranskat)abstract
- We present a combined soft x-ray and high-resolution vacuum-ultraviolet angle-resolved photoemission spectroscopy study of the electron-overdoped cuprate Pr1.3-xLa0.7CexCuO4 (PLCCO). Demonstration of its highly two-dimensional band structure enabled precise determination of the in-plane self-energy dominated by electron-electron scattering. Through analysis of this self-energy and the Fermi liquid cut-off energy scale, we find-in contrast to hole-doped cuprates-a momentum isotropic and comparatively weak electron correlation in PLCCO. Yet, the self-energies extracted from multiple oxide systems combine to demonstrate a logarithmic divergent relation between the quasiparticle scattering rate and mass. This constitutes a spectroscopic version of the Kadowaki-Woods relation with an important merit-the demonstration of Fermi liquid quasiparticle lifetime and mass being set by a single energy scale.
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| 5. |
- Kramer, K. P., et al.
(författare)
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Band structure of overdoped cuprate superconductors: Density functional theory matching experiments
- 2019
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Ingår i: Physical Review B. - 2469-9969 .- 2469-9950. ; 99:22
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Tidskriftsartikel (refereegranskat)abstract
- A comprehensive angle-resolved photoemission spectroscopy study of the band structure in singlelayer cuprates is presented with the aim of uncovering universal trends across different materials. Five different hole-and electron-overdoped cuprate superconductors (La1.59Eu0.2Sr0.21CuO4, La1.77Sr0.23CuO4, Bi1.74Pb0.38Sr1.88CuO6+delta, Tl2Ba2CuO6+delta, and Pr1.15La0.7Ce0.15CuO4) have been studied with special focus on the bands with a predominately d-orbital character. Using a light polarization analysis, the e(g) and t(2g) bands are identified across these materials. A clear correlation between the d(3z2-r2) band energy and the apical oxygen distance d(A) is demonstrated. Moreover, the compound dependence of the d(x2-y2) band bottom and the t(2g) band top is revealed. A direct comparison to density functional theory (DFT) calculations employing hybrid exchange-correlation functionals demonstrates excellent agreement. We thus conclude that the DFT methodology can be used to describe the global band structure of overdoped single-layer cuprates on both the hole-and electron-doped side.
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