| 1. |
- Simutis, Gediminas, et al.
(author)
-
Single-domain stripe order in a high-temperature superconductor
- 2022
-
In: Communications Physics. - : Springer Science and Business Media LLC. - 2399-3650. ; 5:1
-
Journal article (peer-reviewed)abstract
- The coupling of spin, charge and lattice degrees of freedom results in the emergence of novel states of matter across many classes of strongly correlated electron materials. A model example is unconventional superconductivity, which is widely believed to arise from the coupling of electrons via spin excitations. In cuprate high-temperature superconductors, the interplay of charge and spin degrees of freedom is also reflected in a zoo of charge and spin-density wave orders that are intertwined with superconductivity. A key question is whether the different types of density waves merely coexist or are indeed directly coupled. Here we profit from a neutron scattering technique with superior beam-focusing that allows us to probe the subtle spin-density wave order in the prototypical high-temperature superconductor La1.88Sr0.12CuO4 under applied uniaxial pressure to demonstrate that the two density waves respond to the external tuning parameter in the same manner. Our result shows that suitable models for high-temperature superconductivity must equally account for charge and spin degrees of freedom via uniaxial charge-spin stripe fluctuations.
|
|
| 2. |
- Küspert, Julia, et al.
(author)
-
Pseudogap suppression by competition with superconductivity in La-based cuprates
- 2022
-
In: Physical Review Research. - 2643-1564. ; 4:4
-
Journal article (peer-reviewed)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.
|
|
| 3. |
- Matt, C. E., et al.
(author)
-
Direct observation of orbital hybridisation in a cuprate superconductor
- 2018
-
In: Nature Communications. - : Nature Publishing Group. - 2041-1723. ; 9
-
Journal article (peer-reviewed)abstract
- The minimal ingredients to explain the essential physics of layered copper-oxide (cuprates) materials remains heavily debated. Effective low-energy single-band models of the copper-oxygen orbitals are widely used because there exists no strong experimental evidence supporting multi-band structures. Here, we report angle-resolved photoelectron spectroscopy experiments on La-based cuprates that provide direct observation of a two-band structure. This electronic structure, qualitatively consistent with density functional theory, is parametrised by a two-orbital (d(x2-y2) and d(z2)) tight-binding model. We quantify the orbital hybridisation which provides an explanation for the Fermi surface topology and the proximity of the van-Hove singularity to the Fermi level. Our analysis leads to a unification of electronic hopping parameters for single-layer cuprates and we conclude that hybridisation, restraining d-wave pairing, is an important optimisation element for superconductivity.
|
|
| 4. |
- Matt, C. E., et al.
(author)
-
Electron scattering, charge order, and pseudogap physics in La1.6-xNd0.4SrxCuO4 : An angle-resolved photoemission spectroscopy study
- 2015
-
In: Physical Review B. Condensed Matter and Materials Physics. - : American Physical Society. - 1098-0121 .- 1550-235X. ; 92:13
-
Journal article (peer-reviewed)abstract
- We report an angle-resolved photoemission study of the charge stripe ordered La1.6-xNd0.4SrxCuO4 (Nd-LSCO) system. A comparative and quantitative line-shape analysis is presented as the system evolves from the overdoped regime into the charge ordered phase. On the overdoped side (x = 0.20), a normal-state antinodal spectral gap opens upon cooling below 80 K. In this process, spectral weight is preserved but redistributed to larger energies. A correlation between this spectral gap and electron scattering is found. A different line shape is observed in the antinodal region of charge ordered Nd-LSCO x = 1/8. Significant low-energy spectral weight appears to be lost. These observations are discussed in terms of spectral-weight redistribution and gapping originating from charge stripe ordering.
|
|
| 5. |
- von Arx, Karin, 1993, et al.
(author)
-
Fate of charge order in overdoped La-based cuprates
- 2023
-
In: NPJ QUANTUM MATERIALS. - : Springer Nature. - 2397-4648. ; 8:1
-
Journal article (peer-reviewed)abstract
- In high-temperature cuprate superconductors, stripe order refers broadly to a coupled spin and charge modulation with a commensuration of eight and four lattice units, respectively. How this stripe order evolves across optimal doping remains a controversial question. Here we present a systematic resonant inelastic x-ray scattering study of weak charge correlations in La2-xSrxCuO4 and La1.8-xEu0.2SrxCuO4. Ultra high energy resolution experiments demonstrate the importance of the separation of inelastic and elastic scattering processes. Long-range temperature-dependent stripe order is only found below optimal doping. At higher doping, short-range temperature-independent correlations are present up to the highest doping measured. This transformation is distinct from and preempts the pseudogap critical doping. We argue that the doping and temperature-independent short-range correlations originate from unresolved electron-phonon coupling that broadly peaks at the stripe ordering vector. In La2-xSrxCuO4, long-range static stripe order vanishes around optimal doping and we discuss both quantum critical and crossover scenarios.
|
|
| 6. |
- Wang, Qisi, et al.
(author)
-
High-Temperature Charge-Stripe Correlations in La1.675Eu0.2Sr0.125CuO4
- 2020
-
In: Physical Review Letters. - : AMER PHYSICAL SOC. - 1079-7114 .- 0031-9007. ; 124:18
-
Journal article (peer-reviewed)abstract
- We use resonant inelastic x-ray scattering to investigate charge-stripe correlations in La1.675Eu0.2Sr0.125CuO4. By differentiating elastic from inelastic scattering, it is demonstrated that charge-stripe correlations precede both the structural low-temperature tetragonal phase and the transport-defined pseudogap onset. The scattering peak amplitude from charge stripes decays approximately as T-2 towards our detection limit. The in-plane integrated intensity, however, remains roughly temperature independent. Therefore, although the incommensurability shows a remarkably large increase at high temperature, our results are interpreted via a single scattering constituent. In fact, direct comparison to other stripe-ordered compounds (La1.875Ba0.125CuO4, La1.475Nd0.4Sr0.125CuO4, and La1.875Sr0.125CuO4) suggests a roughly constant integrated scattering intensity across all these compounds. Our results therefore provide a unifying picture for the charge-stripe ordering in La-based cuprates. As charge correlations in La1.675Eu0.2Sr0.125CuO4 extend beyond the low-temperature tetragonal and pseudogap phase, their emergence heralds a spontaneous symmetry breaking in this compound.
|
|
| 7. |
- Wang, Q., et al.
(author)
-
Uniaxial pressure induced stripe order rotation in La 1.88 Sr 0.12 CuO 4
- 2022
-
In: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723 .- 2041-1723. ; 13:1
-
Journal article (peer-reviewed)abstract
- Static stripe order is detrimental to superconductivity. Yet, it has been proposed that transverse stripe fluctuations may enhance the inter-stripe Josephson coupling and thus promote superconductivity. Direct experimental studies of stripe dynamics, however, remain difficult. From a strong-coupling perspective, transverse stripe fluctuations are realized in the form of dynamic “kinks”—sideways shifting stripe sections. Here, we show how modest uniaxial pressure tuning reorganizes directional kink alignment. Our starting point is La1.88Sr0.12CuO4 where transverse kink ordering results in a rotation of stripe order away from the crystal axis. Application of mild uniaxial pressure changes the ordering pattern and pins the stripe order to the crystal axis. This reordering occurs at a much weaker pressure than that to detwin the stripe domains and suggests a rather weak transverse stripe stiffness. Weak spatial stiffness and transverse quantum fluctuations are likely key prerequisites for stripes to coexist with superconductivity.
|
|
| 8. |
- Wang, Qisi, et al.
(author)
-
Uniaxial pressure induced stripe order rotation in La1.88Sr0.12CuO4
- 2022
-
In: Nature Communications. - : Springer Nature. - 2041-1723. ; 13:1
-
Journal article (peer-reviewed)abstract
- Static stripe order is detrimental to superconductivity. Yet, it has been proposed that transverse stripe fluctuations may enhance the inter-stripe Josephson coupling and thus promote superconductivity. Direct experimental studies of stripe dynamics, however, remain difficult. From a strong-coupling perspective, transverse stripe fluctuations are realized in the form of dynamic "kinks"-sideways shifting stripe sections. Here, we show how modest uniaxial pressure tuning reorganizes directional kink alignment. Our starting point is La1.88Sr0.12CuO4 where transverse kink ordering results in a rotation of stripe order away from the crystal axis. Application of mild uniaxial pressure changes the ordering pattern and pins the stripe order to the crystal axis. This reordering occurs at a much weaker pressure than that to detwin the stripe domains and suggests a rather weak transverse stripe stiffness. Weak spatial stiffness and transverse quantum fluctuations are likely key prerequisites for stripes to coexist with superconductivity. Transverse stripe order fluctuations may promote superconductivity, but experimental verifications remain difficult. Here, the authors report that a mild uniaxial pressure changes the ordering pattern and pins the stripe order to the crystal axis in La1.88Sr0.12CuO4.
|
|
| 9. |
- Chang, J., et al.
(author)
-
Electronic structure near the 1/8-anomaly in La-based cuprates
- 2008
-
In: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 10
-
Journal article (peer-reviewed)abstract
- We report an angle-resolved photoemission study of the electronic structure of the pseudogap state in La1.48Nd0.4Sr0.12CuO4 (T-c < 7 K). Two opposite dispersing Fermi arcs are the main result of this study. Several scenarios that can explain this observation are discussed.
|
|
| 10. |
- Razzoli, E., et al.
(author)
-
The Fermi surface and band folding in La2-xSrxCuO4, probed by angle-resolved photoemission
- 2010
-
In: New Journal of Physics. - : IOP Publishing. - 1367-2630. ; 12, s. 125003-
-
Journal article (peer-reviewed)abstract
- A systematic angle-resolved photoemission study of the electronic structure of La2-xSrxCuO4 in a wide doping range is presented in this paper. In addition to the main energy band, we observed a weaker additional band, the (pi, pi) folded band, which shows unusual doping dependence. The appearance of the folded band suggests that a Fermi surface reconstruction is doping dependent and could already occur at zero magnetic field.
|
|
