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Asmara TC, Green RJ, Suter A, Wei Y, Zhang W, Knez D, Harris G, Tseng Y, Yu T, Betto D, Garcia-Fernandez M, Agrestini S, Klein YM, Kumar N, Galdino CW, Salman Z, Prokscha T, Medarde M, Müller E, Soh Y, Brookes NB, Zhou KJ, Radovic M, Schmitt T. Emergence of Interfacial Magnetism in Strongly-Correlated Nickelate-Titanate Superlattices. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024:e2310668. [PMID: 39101291 DOI: 10.1002/adma.202310668] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Revised: 06/21/2024] [Indexed: 08/06/2024]
Abstract
Strongly-correlated transition-metal oxides are widely known for their various exotic phenomena. This is exemplified by rare-earth nickelates such as LaNiO3, which possess intimate interconnections between their electronic, spin, and lattice degrees of freedom. Their properties can be further enhanced by pairing them in hybrid heterostructures, which can lead to hidden phases and emergent phenomena. An important example is the LaNiO3/LaTiO3 superlattice, where an interlayer electron transfer has been observed from LaTiO3 into LaNiO3 leading to a high-spin state. However, macroscopic emergence of magnetic order associated with this high-spin state has so far not been observed. Here, by using muon spin rotation, x-ray absorption, and resonant inelastic x-ray scattering, direct evidence of an emergent antiferromagnetic order with high magnon energy and exchange interactions at the LaNiO3/LaTiO3 interface is presented. As the magnetism is purely interfacial, a single LaNiO3/LaTiO3 interface can essentially behave as an atomically thin strongly-correlated quasi-2D antiferromagnet, potentially allowing its technological utilization in advanced spintronic devices. Furthermore, its strong quasi-2D magnetic correlations, orbitally-polarized planar ligand holes, and layered superlattice design make its electronic, magnetic, and lattice configurations resemble the precursor states of superconducting cuprates and nickelates, but with an S→1 spin state instead.
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Hirsbrunner M, Mikheenkova A, Törnblom P, House RA, Zhang W, Asmara TC, Wei Y, Schmitt T, Rensmo H, Mukherjee S, Hahlin M, Duda LC. Vibrationally-resolved RIXS reveals OH-group formation in oxygen redox active Li-ion battery cathodes. Phys Chem Chem Phys 2024; 26:19460-19468. [PMID: 38973766 PMCID: PMC11253246 DOI: 10.1039/d4cp01766h] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2024] [Accepted: 06/29/2024] [Indexed: 07/09/2024]
Abstract
Vibrationally-resolved resonant inelastic X-ray scattering (VR-RIXS) at the O K-edge is emerging as a powerful tool for identifying embedded molecules in lithium-ion battery cathodes. Here, we investigate two known oxygen redox-active cathode materials: the commercial LixNi0.90Co0.05Al0.05O2 (NCA) used in electric vehicles and the high-capacity cathode material Li1.2Ni0.13Co0.13Mn0.54O2 (LRNMC) for next-generation Li-ion batteries. We report the detection of a novel vibrational RIXS signature for Li-ion battery cathodes appearing in the O K pre-peak above 533 eV that we attribute to OH-groups. We discuss likely locations and pathways for OH-group formation and accumulation throughout the active cathode material. Initial-cycle behaviour for LRNMC shows that OH-signal strength correlates with the cathodes state of charge, though reversibility is incomplete. The OH-group RIXS signal strength in long-term cycled NCA is retained. Thus, VR-RIXS offers a path for gaining new insights to oxygen reactions in battery materials.
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Wang Q, Mustafi S, Fogh E, Astrakhantsev N, He Z, Biało I, Chan Y, Martinelli L, Horio M, Ivashko O, Shaik NE, Arx KV, Sassa Y, Paris E, Fischer MH, Tseng Y, Christensen NB, Galdi A, Schlom DG, Shen KM, Schmitt T, Rønnow HM, Chang J. Magnon interactions in a moderately correlated Mott insulator. Nat Commun 2024; 15:5348. [PMID: 38914556 PMCID: PMC11196644 DOI: 10.1038/s41467-024-49714-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Accepted: 06/17/2024] [Indexed: 06/26/2024] Open
Abstract
Quantum fluctuations in low-dimensional systems and near quantum phase transitions have significant influences on material properties. Yet, it is difficult to experimentally gauge the strength and importance of quantum fluctuations. Here we provide a resonant inelastic x-ray scattering study of magnon excitations in Mott insulating cuprates. From the thin film of SrCuO2, single- and bi-magnon dispersions are derived. Using an effective Heisenberg Hamiltonian generated from the Hubbard model, we show that the single-magnon dispersion is only described satisfactorily when including significant quantum corrections stemming from magnon-magnon interactions. Comparative results on La2CuO4 indicate that quantum fluctuations are much stronger in SrCuO2 suggesting closer proximity to a magnetic quantum critical point. Monte Carlo calculations reveal that other magnetic orders may compete with the antiferromagnetic Néel order as the ground state. Our results indicate that SrCuO2-due to strong quantum fluctuations-is a unique starting point for the exploration of novel magnetic ground states.
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Martinelli L, Wohlfeld K, Pelliciari J, Arpaia R, Brookes NB, Di Castro D, Fernandez MG, Kang M, Krockenberger Y, Kummer K, McNally DE, Paris E, Schmitt T, Yamamoto H, Walters A, Zhou KJ, Braicovich L, Comin R, Sala MM, Devereaux TP, Daghofer M, Ghiringhelli G. Collective Nature of Orbital Excitations in Layered Cuprates in the Absence of Apical Oxygens. PHYSICAL REVIEW LETTERS 2024; 132:066004. [PMID: 38394564 DOI: 10.1103/physrevlett.132.066004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Revised: 10/27/2023] [Accepted: 12/21/2023] [Indexed: 02/25/2024]
Abstract
We have investigated the 3d orbital excitations in CaCuO_{2} (CCO), Nd_{2}CuO_{4} (NCO), and La_{2}CuO_{4} (LCO) using high-resolution resonant inelastic x-ray scattering. In LCO they behave as well-localized excitations, similarly to several other cuprates. On the contrary, in CCO and NCO the d_{xy} orbital clearly disperses, pointing to a collective character of this excitation (orbiton) in compounds without apical oxygen. We ascribe the origin of the dispersion as stemming from a substantial next-nearest-neighbor (NNN) orbital superexchange. Such an exchange leads to the liberation of the orbiton from its coupling to magnons, which is associated with the orbiton hopping between nearest neighbor copper sites. Finally, we show that the exceptionally large NNN orbital superexchange can be traced back to the absence of apical oxygens suppressing the charge transfer energy.
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Mikheenkova A, Mukherjee S, Hirsbrunner M, Törnblom P, Tai CW, Segre CU, Ding Y, Zhang W, Asmara TC, Wei Y, Schmitt T, Rensmo H, Duda L, Hahlin M. The role of oxygen in automotive grade lithium-ion battery cathodes: an atomistic survey of ageing. JOURNAL OF MATERIALS CHEMISTRY. A 2024; 12:2465-2478. [PMID: 38269086 PMCID: PMC10805348 DOI: 10.1039/d3ta05516g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Accepted: 12/06/2023] [Indexed: 01/26/2024]
Abstract
The rising demand for high-performance lithium-ion batteries, pivotal to electric transportation, hinges on key materials like the Ni-rich layered oxide LiNixCoyAlzO2 (NCA) used in cathodes. The present study investigates the redox mechanisms, with particular focus on the role of oxygen in commercial NCA electrodes, both fresh and aged under various conditions (aged cells have performed >900 cycles until a cathode capacity retention of ∼80%). Our findings reveal that oxygen participates in charge compensation during NCA delithiation, both through changes in transition metal (TM)-O bond hybridization and formation of partially reversible O2, the latter occurs already below 3.8 V vs. Li/Li+. Aged NCA material undergoes more significant changes in TM-O bond hybridization when cycling above 50% SoC, while reversible O2 formation is maintained. Nickel is found to be redox active throughout the entire delithiation and shows a more classical oxidation state change during cycling with smaller changes in the Ni-O hybridization. By contrast, Co redox activity relies on a stronger change in Co-O hybridization, with only smaller Co oxidation state changes. The Ni-O bond displays an almost twice as large change in its bond length on cycling as the Co-O bond. The Ni-O6 octahedra are similar in size to the Co-O6 octahedra in the delithiated state, but are larger in the lithiated state, a size difference that increases with battery ageing. These contrasting redox activities are reflected directly in structural changes. The NCA material exhibits the formation of nanopores upon ageing, and a possible connection to oxygen redox activity is discussed. The difference in interaction of Ni and Co with oxygen provides a key understanding of the mechanism and the electrochemical instability of Ni-rich layered transition metal oxide electrodes. Our research specifically highlights the significance of the role of oxygen in the electrochemical performance of electric-vehicle-grade NCA electrodes, offering important insights for the creation of next-generation long-lived lithium-ion batteries.
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Liu R, Zhang W, Wei Y, Tao Z, Asmara TC, Li Y, Strocov VN, Yu R, Si Q, Schmitt T, Lu X. Nematic Spin Correlations Pervading the Phase Diagram of FeSe_{1-x}S_{x}. PHYSICAL REVIEW LETTERS 2024; 132:016501. [PMID: 38242670 DOI: 10.1103/physrevlett.132.016501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/16/2023] [Accepted: 12/08/2023] [Indexed: 01/21/2024]
Abstract
We use resonant inelastic x-ray scattering (RIXS) at the Fe-L_{3} edge to study the spin excitations of uniaxial-strained and unstrained FeSe_{1-x}S_{x} (0≤x≤0.21) samples. The measurements on unstrained samples reveal dispersive spin excitations in all doping levels, which show only minor doping dependence in energy dispersion, lifetime, and intensity, indicating that high-energy spin excitations are only marginally affected by sulfur doping. RIXS measurements on uniaxial-strained samples reveal that the high-energy spin-excitation anisotropy observed previously in FeSe is also present in the doping range 0200 K in x=0.18 and reaches a maximum around the nematic quantum critical doping (x_{c}≈0.17). Since the spin-excitation anisotropy directly reflects the existence of nematic spin correlations, our results indicate that high-energy nematic spin correlations pervade the regime of nematicity in the phase diagram and are enhanced by the nematic quantum criticality. These results emphasize the essential role of spin fluctuations in driving electronic nematicity and highlight the capability of uniaxial strain in tuning spin excitations in quantum materials hosting strong magnetoelastic coupling and electronic nematicity.
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Lu AT, Fei Z, Haghani A, Robeck TR, Zoller JA, Li CZ, Lowe R, Yan Q, Zhang J, Vu H, Ablaeva J, Acosta-Rodriguez VA, Adams DM, Almunia J, Aloysius A, Ardehali R, Arneson A, Baker CS, Banks G, Belov K, Bennett NC, Black P, Blumstein DT, Bors EK, Breeze CE, Brooke RT, Brown JL, Carter GG, Caulton A, Cavin JM, Chakrabarti L, Chatzistamou I, Chen H, Cheng K, Chiavellini P, Choi OW, Clarke SM, Cooper LN, Cossette ML, Day J, DeYoung J, DiRocco S, Dold C, Ehmke EE, Emmons CK, Emmrich S, Erbay E, Erlacher-Reid C, Faulkes CG, Ferguson SH, Finno CJ, Flower JE, Gaillard JM, Garde E, Gerber L, Gladyshev VN, Gorbunova V, Goya RG, Grant MJ, Green CB, Hales EN, Hanson MB, Hart DW, Haulena M, Herrick K, Hogan AN, Hogg CJ, Hore TA, Huang T, Izpisua Belmonte JC, Jasinska AJ, Jones G, Jourdain E, Kashpur O, Katcher H, Katsumata E, Kaza V, Kiaris H, Kobor MS, Kordowitzki P, Koski WR, Krützen M, Kwon SB, Larison B, Lee SG, Lehmann M, Lemaitre JF, Levine AJ, Li C, Li X, Lim AR, Lin DTS, Lindemann DM, Little TJ, Macoretta N, Maddox D, Matkin CO, Mattison JA, McClure M, Mergl J, Meudt JJ, Montano GA, Mozhui K, Munshi-South J, Naderi A, Nagy M, Narayan P, Nathanielsz PW, Nguyen NB, Niehrs C, O'Brien JK, O'Tierney Ginn P, Odom DT, Ophir AG, Osborn S, Ostrander EA, Parsons KM, Paul KC, Pellegrini M, Peters KJ, Pedersen AB, Petersen JL, Pietersen DW, Pinho GM, Plassais J, Poganik JR, Prado NA, Reddy P, Rey B, Ritz BR, Robbins J, Rodriguez M, Russell J, Rydkina E, Sailer LL, Salmon AB, Sanghavi A, Schachtschneider KM, Schmitt D, Schmitt T, Schomacher L, Schook LB, Sears KE, Seifert AW, Seluanov A, Shafer ABA, Shanmuganayagam D, Shindyapina AV, Simmons M, Singh K, Sinha I, Slone J, Snell RG, Soltanmaohammadi E, Spangler ML, Spriggs MC, Staggs L, Stedman N, Steinman KJ, Stewart DT, Sugrue VJ, Szladovits B, Takahashi JS, Takasugi M, Teeling EC, Thompson MJ, Van Bonn B, Vernes SC, Villar D, Vinters HV, Wallingford MC, Wang N, Wayne RK, Wilkinson GS, Williams CK, Williams RW, Yang XW, Yao M, Young BG, Zhang B, Zhang Z, Zhao P, Zhao Y, Zhou W, Zimmermann J, Ernst J, Raj K, Horvath S. Author Correction: Universal DNA methylation age across mammalian tissues. NATURE AGING 2023; 3:1462. [PMID: 37674040 PMCID: PMC10645586 DOI: 10.1038/s43587-023-00499-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/08/2023]
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Lu AT, Fei Z, Haghani A, Robeck TR, Zoller JA, Li CZ, Lowe R, Yan Q, Zhang J, Vu H, Ablaeva J, Acosta-Rodriguez VA, Adams DM, Almunia J, Aloysius A, Ardehali R, Arneson A, Baker CS, Banks G, Belov K, Bennett NC, Black P, Blumstein DT, Bors EK, Breeze CE, Brooke RT, Brown JL, Carter GG, Caulton A, Cavin JM, Chakrabarti L, Chatzistamou I, Chen H, Cheng K, Chiavellini P, Choi OW, Clarke SM, Cooper LN, Cossette ML, Day J, DeYoung J, DiRocco S, Dold C, Ehmke EE, Emmons CK, Emmrich S, Erbay E, Erlacher-Reid C, Faulkes CG, Ferguson SH, Finno CJ, Flower JE, Gaillard JM, Garde E, Gerber L, Gladyshev VN, Gorbunova V, Goya RG, Grant MJ, Green CB, Hales EN, Hanson MB, Hart DW, Haulena M, Herrick K, Hogan AN, Hogg CJ, Hore TA, Huang T, Izpisua Belmonte JC, Jasinska AJ, Jones G, Jourdain E, Kashpur O, Katcher H, Katsumata E, Kaza V, Kiaris H, Kobor MS, Kordowitzki P, Koski WR, Krützen M, Kwon SB, Larison B, Lee SG, Lehmann M, Lemaitre JF, Levine AJ, Li C, Li X, Lim AR, Lin DTS, Lindemann DM, Little TJ, Macoretta N, Maddox D, Matkin CO, Mattison JA, McClure M, Mergl J, Meudt JJ, Montano GA, Mozhui K, Munshi-South J, Naderi A, Nagy M, Narayan P, Nathanielsz PW, Nguyen NB, Niehrs C, O'Brien JK, O'Tierney Ginn P, Odom DT, Ophir AG, Osborn S, Ostrander EA, Parsons KM, Paul KC, Pellegrini M, Peters KJ, Pedersen AB, Petersen JL, Pietersen DW, Pinho GM, Plassais J, Poganik JR, Prado NA, Reddy P, Rey B, Ritz BR, Robbins J, Rodriguez M, Russell J, Rydkina E, Sailer LL, Salmon AB, Sanghavi A, Schachtschneider KM, Schmitt D, Schmitt T, Schomacher L, Schook LB, Sears KE, Seifert AW, Seluanov A, Shafer ABA, Shanmuganayagam D, Shindyapina AV, Simmons M, Singh K, Sinha I, Slone J, Snell RG, Soltanmaohammadi E, Spangler ML, Spriggs MC, Staggs L, Stedman N, Steinman KJ, Stewart DT, Sugrue VJ, Szladovits B, Takahashi JS, Takasugi M, Teeling EC, Thompson MJ, Van Bonn B, Vernes SC, Villar D, Vinters HV, Wallingford MC, Wang N, Wayne RK, Wilkinson GS, Williams CK, Williams RW, Yang XW, Yao M, Young BG, Zhang B, Zhang Z, Zhao P, Zhao Y, Zhou W, Zimmermann J, Ernst J, Raj K, Horvath S. Universal DNA methylation age across mammalian tissues. NATURE AGING 2023; 3:1144-1166. [PMID: 37563227 PMCID: PMC10501909 DOI: 10.1038/s43587-023-00462-6] [Citation(s) in RCA: 64] [Impact Index Per Article: 64.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Accepted: 06/21/2023] [Indexed: 08/12/2023]
Abstract
Aging, often considered a result of random cellular damage, can be accurately estimated using DNA methylation profiles, the foundation of pan-tissue epigenetic clocks. Here, we demonstrate the development of universal pan-mammalian clocks, using 11,754 methylation arrays from our Mammalian Methylation Consortium, which encompass 59 tissue types across 185 mammalian species. These predictive models estimate mammalian tissue age with high accuracy (r > 0.96). Age deviations correlate with human mortality risk, mouse somatotropic axis mutations and caloric restriction. We identified specific cytosines with methylation levels that change with age across numerous species. These sites, highly enriched in polycomb repressive complex 2-binding locations, are near genes implicated in mammalian development, cancer, obesity and longevity. Our findings offer new evidence suggesting that aging is evolutionarily conserved and intertwined with developmental processes across all mammals.
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Strocov VN, Lev LL, Alarab F, Constantinou P, Wang X, Schmitt T, Stock TJZ, Nicolaï L, Očenášek J, Minár J. High-energy photoemission final states beyond the free-electron approximation. Nat Commun 2023; 14:4827. [PMID: 37563126 PMCID: PMC10415355 DOI: 10.1038/s41467-023-40432-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Accepted: 07/26/2023] [Indexed: 08/12/2023] Open
Abstract
Three-dimensional (3D) electronic band structure is fundamental for understanding a vast diversity of physical phenomena in solid-state systems, including topological phases, interlayer interactions in van der Waals materials, dimensionality-driven phase transitions, etc. Interpretation of ARPES data in terms of 3D electron dispersions is commonly based on the free-electron approximation for the photoemission final states. Our soft-X-ray ARPES data on Ag metal reveals, however, that even at high excitation energies the final states can be a way more complex, incorporating several Bloch waves with different out-of-plane momenta. Such multiband final states manifest themselves as a complex structure and added broadening of the spectral peaks from 3D electron states. We analyse the origins of this phenomenon, and trace it to other materials such as Si and GaN. Our findings are essential for accurate determination of the 3D band structure over a wide range of materials and excitation energies in the ARPES experiment.
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Tseng Y, Paris E, Schmidt KP, Zhang W, Asmara TC, Bag R, Strocov VN, Singh S, Schlappa J, Rønnow HM, Schmitt T. Momentum-resolved spin-conserving two-triplon bound state and continuum in a cuprate ladder. COMMUNICATIONS PHYSICS 2023; 6:138. [PMID: 38665396 PMCID: PMC11041747 DOI: 10.1038/s42005-023-01250-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 05/23/2023] [Indexed: 04/28/2024]
Abstract
Studying multi-particle elementary excitations has provided unique access to understand collective many-body phenomena in correlated electronic materials, paving the way towards constructing microscopic models. In this work, we perform O K-edge resonant inelastic X-ray scattering (RIXS) on the quasi-one-dimensional cuprate Sr 14 Cu 24 O 41 with weakly-doped spin ladders. The RIXS signal is dominated by a dispersing sharp mode ~ 270 meV on top of a damped incoherent component ~ 400-500 meV. Comparing with model calculations using the perturbative continuous unitary transformations method, the two components resemble the spin-conserving ΔS = 0 two-triplon bound state and continuum excitations in the spin ladders. Such multi-spin response with long-lived ΔS = 0 excitons is central to several exotic magnetic properties featuring Majorana fermions, yet remains unexplored given the generally weak cross-section with other experimental techniques. By investigating a simple spin-ladder model system, our study provides valuable insight into low-dimensional quantum magnetism.
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Popescu DG, Husanu MA, Constantinou PC, Filip LD, Trupina L, Bucur CI, Pasuk I, Chirila C, Hrib LM, Stancu V, Pintilie L, Schmitt T, Teodorescu CM, Strocov VN. Experimental Band Structure of Pb(Zr,Ti)O 3 : Mechanism of Ferroelectric Stabilization. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2205476. [PMID: 36592417 PMCID: PMC9951575 DOI: 10.1002/advs.202205476] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Revised: 12/07/2022] [Indexed: 06/17/2023]
Abstract
Pb(Zr,Ti)O3 (PZT) is the most common ferroelectric (FE) material widely used in solid-state technology. Despite intense studies of PZT over decades, its intrinsic band structure, electron energy depending on 3D momentum k, is still unknown. Here, Pb(Zr0.2 Ti0.8 )O3 using soft-X-ray angle-resolved photoelectron spectroscopy (ARPES) is explored. The enhanced photoelectron escape depth in this photon energy range allows sharp intrinsic definition of the out-of-plane momentum k and thereby of the full 3D band structure. Furthermore, the problem of sample charging due to the inherently insulating nature of PZT is solved by using thin-film PZT samples, where a thickness-induced self-doping results in their heavy doping. For the first time, the soft-X-ray ARPES experiments deliver the intrinsic 3D band structure of PZT as well as the FE-polarization dependent electrostatic potential profile across the PZT film deposited on SrTiO3 and Lax SrMn1- x O3 substrates. The negative charges near the surface, required to stabilize the FE state pointing away from the sample (P+), are identified as oxygen vacancies creating localized in-gap states below the Fermi energy. For the opposite polarization state (P-), the positive charges near the surface are identified as cation vacancies resulting from non-ideal stoichiometry of the PZT film as deduced from quantitative XPS measurements.
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Schüler M, Schmitt T, Werner P. Probing magnetic orbitals and Berry curvature with circular dichroism in resonant inelastic X-ray scattering. NPJ QUANTUM MATERIALS 2023; 8:6. [PMID: 38666242 PMCID: PMC11041711 DOI: 10.1038/s41535-023-00538-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/28/2022] [Accepted: 01/04/2023] [Indexed: 04/28/2024]
Abstract
Resonant inelastic X-ray scattering (RIXS) can probe localized excitations at selected atoms in materials, including particle-hole transitions between the valence and conduction bands. These transitions are governed by fundamental properties of the corresponding Bloch wave functions, including orbital and magnetic degrees of freedom, and quantum geometric properties such as the Berry curvature. In particular, orbital angular momentum (OAM), which is closely linked to the Berry curvature, can exhibit a nontrivial momentum dependence. We demonstrate how information on such OAM textures can be extracted from the circular dichroism in RIXS. Based on accurate modeling with a first-principles treatment of the key ingredient-the light-matter interaction-we simulate dichroic RIXS spectra for the prototypical transition-metal dichalcogenide MoSe2 and the two-dimensional topological insulator 1T'-MoS2. Guided by an intuitive picture of the optical selection rules, we discuss how the momentum-dependent OAM manifests itself in the dichroic RIXS signal if one controls the momentum transfer. Our calculations are performed for typical experimental geometries and parameter regimes, and demonstrate the possibility of observing the predicted circular dichroism in forthcoming experiments. Thus, our work establishes a new avenue for observing Berry curvature and topological states in quantum materials.
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von Arx K, Wang Q, Mustafi S, Mazzone DG, Horio M, Mukkattukavil DJ, Pomjakushina E, Pyon S, Takayama T, Takagi H, Kurosawa T, Momono N, Oda M, Brookes NB, Betto D, Zhang W, Asmara TC, Tseng Y, Schmitt T, Sassa Y, Chang J. Fate of charge order in overdoped La-based cuprates. NPJ QUANTUM MATERIALS 2023; 8:7. [PMID: 38666240 PMCID: PMC11041719 DOI: 10.1038/s41535-023-00539-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/23/2022] [Accepted: 01/09/2023] [Indexed: 04/28/2024]
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.
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Yu T, Wright J, Khalsa G, Pamuk B, Chang CS, Matveyev Y, Wang X, Schmitt T, Feng D, Muller DA, Xing HG, Jena D, Strocov VN. Momentum-resolved electronic structure and band offsets in an epitaxial NbN/GaN superconductor/semiconductor heterojunction. SCIENCE ADVANCES 2021; 7:eabi5833. [PMID: 34936435 PMCID: PMC8694612 DOI: 10.1126/sciadv.abi5833] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/21/2021] [Accepted: 11/05/2021] [Indexed: 06/14/2023]
Abstract
The electronic structure of heterointerfaces is a pivotal factor for their device functionality. We use soft x-ray angle-resolved photoelectron spectroscopy to directly measure the momentum-resolved electronic band structures on both sides of the Schottky heterointerface formed by epitaxial films of the superconducting NbN on semiconducting GaN, and determine their momentum-dependent interfacial band offset as well as the band-bending profile. We find, in particular, that the Fermi states in NbN are well separated in energy and momentum from the states in GaN, excluding any notable electronic cross-talk of the superconducting states in NbN to GaN. We support the experimental findings with first-principles calculations for bulk NbN and GaN. The Schottky barrier height obtained from photoemission is corroborated by electronic transport and optical measurements. The momentum-resolved understanding of electronic properties of interfaces elucidated in our work opens up new frontiers for the quantum materials where interfacial states play a defining role.
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Hudemann C, Maglie R, Beckert B, Didona D, Schmitt T, Tikkanen R, Hashimoto T, Waschke J, Hertl M, Eming R. 009 Human desmocollin 3-specific IgG antibodies are pathogenic in a humanized HLA-class II transgenic mouse model of pemphigus. J Invest Dermatol 2021. [DOI: 10.1016/j.jid.2021.08.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Hudemann C, Maglie R, Llamazares M, Beckert B, Didona D, Tikkanen R, Schmitt T, Hashimoto T, Waschke J, Hertl M, Eming R. Human desmocollin 3-specific IgG antibodies are pathogenic in a humanized HLA-class II transgenic mouse model of pemphigus. J Invest Dermatol 2021; 142:915-923.e3. [PMID: 34265330 DOI: 10.1016/j.jid.2021.06.017] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 05/19/2021] [Accepted: 06/10/2021] [Indexed: 02/07/2023]
Abstract
Pemphigus is a potentially lethal autoimmune bullous skin disorder, which is associated with IgG autoantibodies against desmoglein 3 (Dsg3) and Dsg1. Notably, a subset of pemphigus patients presents with a similar clinical phenotype in the absence of anti-Dsg IgG, suggesting the presence of serum IgG reactive with desmosomal components other than Dsg1 or Dsg3. We and others have previously shown that such patients have serum IgG autoantibodies against desmocollin 3 (Dsc3), a component of desmosomes, that induce loss of keratinocyte adhesion ex vivo. Moreover, Dsc3 hypomorphic mice show a severe blistering phenotype of the mucous membrane which is highly characteristic in pemphigus. These findings prompted us to study induction and regulation of anti-human Dsc3 IgG in humanized mice transgenic for HLA-DRB1*04:02, which is a highly prevalent haplotype in pemphigus. We show that IgG from sera of immunized mice induce acantholysis in a dispase-based keratinocyte dissociation assay via the activation of p38 mitogen-activated protein kinases and epidermal growth factor receptor. Passive IgG transfer from mice immunized with recombinant human Dsc3 into neonates did not induce intraepidermal loss of adhesion presumably due to the lack of homology between human and mouse Dsc3. Ex vivo stimulation of splenocytes from Dsc3-immunized mice with human Dsc3 leads to a significant proliferative interferon-γ and interleukin 4 T cell response, which is restricted by HLA-DR/DQ. These findings suggest that induction of pathogenic anti-Dsc3 IgG is associated with Dsc3-specific T cells that recognize Dsc3 in association with HLA-DRB1*04:02.
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Dreger P, Martus P, Holtick U, Ayuk F, Wagner‐Drouet EM, Wulf G, Marks R, Penack O, Koenecke C, von Bonin M, von Tresckow B, Stelljes M, Baldus C, Vucinic V, Mougiakakos D, Topp M, Wolff D, Schroers R, Schmitt M, Schmitt T, Lengerke C, Thomas S, Beelen DW, Bethge W. OUTCOME DETERMINANTS OF COMMERCIAL CAR‐T CELL THERAPY FOR LARGE B‐CELL LYMPHOMA: RESULTS OF THE GLA/DRST REAL WORLD ANALYSIS. Hematol Oncol 2021. [DOI: 10.1002/hon.186_2880] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Savchenko V, Ekholm V, Brumboiu IE, Norman P, Pietzsch A, Föhlisch A, Rubensson JE, Gråsjö J, Björneholm O, Såthe C, Dong M, Schmitt T, McNally D, Lu X, Krasnov P, Polyutov SP, Gel'mukhanov F, Odelius M, Kimberg V. Hydrogen bond effects in multimode nuclear dynamics of acetic acid observed via resonant x-ray scattering. J Chem Phys 2021; 154:214304. [PMID: 34240997 DOI: 10.1063/5.0049966] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A theoretical and experimental study of the gas phase and liquid acetic acid based on resonant inelastic x-ray scattering (RIXS) spectroscopy is presented. We combine and compare different levels of theory for an isolated molecule for a comprehensive analysis, including electronic and vibrational degrees of freedom. The excitation energy scan over the oxygen K-edge absorption reveals nuclear dynamic effects in the core-excited and final electronic states. The theoretical simulations for the monomer and two different forms of the dimer are compared against high-resolution experimental data for pure liquid acetic acid. We show that the theoretical model based on a dimer describes the hydrogen bond formation in the liquid phase well and that this bond formation sufficiently alters the RIXS spectra, allowing us to trace these effects directly from the experiment. Multimode vibrational dynamics is accounted for in our simulations by using a hybrid time-dependent stationary approach for the quantum nuclear wave packet simulations, showing the important role it plays in RIXS.
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Wang Q, von Arx K, Horio M, Mukkattukavil DJ, Küspert J, Sassa Y, Schmitt T, Nag A, Pyon S, Takayama T, Takagi H, Garcia-Fernandez M, Zhou KJ, Chang J. Charge order lock-in by electron-phonon coupling in La 1.675Eu 0.2Sr 0.125CuO 4. SCIENCE ADVANCES 2021; 7:eabg7394. [PMID: 34193430 PMCID: PMC8245032 DOI: 10.1126/sciadv.abg7394] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Accepted: 05/17/2021] [Indexed: 06/13/2023]
Abstract
Charge order is universal to all hole-doped cuprates. Yet, the driving interactions remain an unsolved problem. Electron-electron interaction is widely believed to be essential, whereas the role of electron-phonon interaction is unclear. We report an ultrahigh-resolution resonant inelastic x-ray scattering (RIXS) study of the in-plane bond-stretching phonon mode in stripe-ordered cuprate La1.675Eu0.2Sr0.125CuO4 Phonon softening and lifetime shortening are found around the charge ordering wave vector. In addition to these self-energy effects, the electron-phonon coupling is probed by its proportionality to the RIXS cross section. We find an enhancement of the electron-phonon coupling around the charge-stripe ordering wave vector upon cooling into the low-temperature tetragonal structure phase. These results suggest that, in addition to electronic correlations, electron-phonon coupling contributes substantially to the emergence of long-range charge-stripe order in cuprates.
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Schmitt T, Egu DT, Walter E, Sigmund AM, Eichkorn R, Yazdi A, Schmidt E, Sárdy M, Eming R, Goebeler M, Waschke J. Ca 2+ signalling is critical for autoantibody-induced blistering of human epidermis in pemphigus. Br J Dermatol 2021; 185:595-604. [PMID: 33792909 DOI: 10.1111/bjd.20091] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/26/2021] [Indexed: 02/06/2023]
Abstract
BACKGROUND Pemphigus is a severe bullous autoimmune skin disease. Pemphigus foliaceus (PF) is characterized by antidesmoglein (Dsg) 1 IgG causing epidermal blistering; mucosal pemphigus vulgaris (mPV) by anti-Dsg3 IgG inducing erosions in the mucosa; and mucocutaneous pemphigus vulgaris (PV) by affecting both, with autoantibodies targeting Dsg1 and Dsg3. OBJECTIVES To characterize the Ca2+ flux pathway and delineate its importance in pemphigus pathogenesis and clinical phenotypes caused by different antibody profiles. METHODS Immunoprecipitation, Ca2+ flux analysis, Western blotting, immunofluorescence staining, dissociation assays and a human skin ex vivo model were used. RESULTS PV IgG and PF IgG, but neither Dsg3-specific monoclonal antibody (AK23) nor mPV IgG, caused Ca2+ influx in primary human keratinocytes. Phosphatidylinositol 4-kinase α interacts with Dsg1 but not with Dsg3. Its downstream target - phospholipase-C-γ1 (PLC) - was activated by PV IgG and PF IgG but not AK23 or mPV IgG. PLC releases inositol 1,4,5-trisphosphate (IP3) causing IP3 receptor (IP3R) activation and Ca2+ flux from the endoplasmic reticulum into the cytosol, which stimulates Ca2+ release-activated channels (CRAC)-mediated Ca2+ influx. Inhibitors against PLC, IP3R and CRAC effectively blocked PV IgG and PF IgG-induced Ca2+ influx; ameliorated alterations of Dsg1 and Dsg3 localization, and reorganization of keratin and actin filaments; and inhibited loss of cell adhesion in vitro. Finally, inhibiting PLC or IP3R was protective against PV IgG-induced blister formation and redistribution of Dsg1 and Dsg3 in human skin ex vivo. CONCLUSIONS Ca2+ -mediated signalling is important for epidermal blistering and dependent on the autoantibody profile, which indicates different roles for signalling complexes organized by Dsg1 and Dsg3. Interfering with PLC and Ca2+ signalling may be a promising approach to treat epidermal manifestations of pemphigus.
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Chikina A, Christensen DV, Borisov V, Husanu MA, Chen Y, Wang X, Schmitt T, Radovic M, Nagaosa N, Mishchenko AS, Valentí R, Pryds N, Strocov VN. Band-Order Anomaly at the γ-Al 2O 3/SrTiO 3 Interface Drives the Electron-Mobility Boost. ACS NANO 2021; 15:4347-4356. [PMID: 33661601 DOI: 10.1021/acsnano.0c07609] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The rich functionalities of transition-metal oxides and their interfaces bear an enormous technological potential. Its realization in practical devices requires, however, a significant improvement of yet relatively low electron mobility in oxide materials. Recently, a mobility boost of about 2 orders of magnitude has been demonstrated at the spinel-perovskite γ-Al2O3/SrTiO3 interface compared to the paradigm perovskite-perovskite LaAlO3/SrTiO3 interface. We explore the fundamental physics behind this phenomenon from direct measurements of the momentum-resolved electronic structure of this interface using resonant soft-X-ray angle-resolved photoemission. We find an anomaly in orbital ordering of the mobile electrons in γ-Al2O3/SrTiO3 which depopulates electron states in the top SrTiO3 layer. This rearrangement of the mobile electron system pushes the electron density away from the interface, which reduces its overlap with the interfacial defects and weakens the electron-phonon interaction, both effects contributing to the mobility boost. A crystal-field analysis shows that the band order alters owing to the symmetry breaking between the spinel γ-Al2O3 and perovskite SrTiO3. Band-order engineering, exploiting the fundamental symmetry properties, emerges as another route to boost the performance of oxide devices.
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Schröter NBM, Robredo I, Klemenz S, Kirby RJ, Krieger JA, Pei D, Yu T, Stolz S, Schmitt T, Dudin P, Kim TK, Cacho C, Schnyder A, Bergara A, Strocov VN, de Juan F, Vergniory MG, Schoop LM. Weyl fermions, Fermi arcs, and minority-spin carriers in ferromagnetic CoS 2. SCIENCE ADVANCES 2020; 6:eabd5000. [PMID: 33355138 PMCID: PMC11206217 DOI: 10.1126/sciadv.abd5000] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Accepted: 11/05/2020] [Indexed: 06/12/2023]
Abstract
Magnetic Weyl semimetals are a newly discovered class of topological materials that may serve as a platform for exotic phenomena, such as axion insulators or the quantum anomalous Hall effect. Here, we use angle-resolved photoelectron spectroscopy and ab initio calculations to discover Weyl cones in CoS2, a ferromagnet with pyrite structure that has been long studied as a candidate for half-metallicity, which makes it an attractive material for spintronic devices. We directly observe the topological Fermi arc surface states that link the Weyl nodes, which will influence the performance of CoS2 as a spin injector by modifying its spin polarization at interfaces. In addition, we directly observe a minority-spin bulk electron pocket in the corner of the Brillouin zone, which proves that CoS2 cannot be a true half-metal.
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Hepting M, Li D, Jia CJ, Lu H, Paris E, Tseng Y, Feng X, Osada M, Been E, Hikita Y, Chuang YD, Hussain Z, Zhou KJ, Nag A, Garcia-Fernandez M, Rossi M, Huang HY, Huang DJ, Shen ZX, Schmitt T, Hwang HY, Moritz B, Zaanen J, Devereaux TP, Lee WS. Publisher Correction: Electronic structure of the parent compound of superconducting infinite-layer nickelates. NATURE MATERIALS 2020; 19:1036. [PMID: 32661388 DOI: 10.1038/s41563-020-0761-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
An amendment to this paper has been published and can be accessed via a link at the top of the paper.
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Schröter NBM, Stolz S, Manna K, de Juan F, Vergniory MG, Krieger JA, Pei D, Schmitt T, Dudin P, Kim TK, Cacho C, Bradlyn B, Borrmann H, Schmidt M, Widmer R, Strocov VN, Felser C. Observation and control of maximal Chern numbers in a chiral topological semimetal. Science 2020; 369:179-183. [DOI: 10.1126/science.aaz3480] [Citation(s) in RCA: 59] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Accepted: 05/07/2020] [Indexed: 11/02/2022]
Abstract
Topological semimetals feature protected nodal band degeneracies characterized by a topological invariant known as the Chern number (C). Nodal band crossings with linear dispersion are expected to have at most |C|=4, which sets an upper limit to the magnitude of many topological phenomena in these materials. Here, we show that the chiral crystal palladium gallium (PdGa) displays multifold band crossings, which are connected by exactly four surface Fermi arcs, thus proving that they carry the maximal Chern number magnitude of 4. By comparing two enantiomers, we observe a reversal of their Fermi-arc velocities, which demonstrates that the handedness of chiral crystals can be used to control the sign of their Chern numbers.
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Wang Q, Horio M, von Arx K, Shen Y, John Mukkattukavil D, Sassa Y, Ivashko O, Matt CE, Pyon S, Takayama T, Takagi H, Kurosawa T, Momono N, Oda M, Adachi T, Haidar SM, Koike Y, Tseng Y, Zhang W, Zhao J, Kummer K, Garcia-Fernandez M, Zhou KJ, Christensen NB, Rønnow HM, Schmitt T, Chang J. High-Temperature Charge-Stripe Correlations in La_{1.675}Eu_{0.2}Sr_{0.125}CuO_{4}. PHYSICAL REVIEW LETTERS 2020; 124:187002. [PMID: 32441965 DOI: 10.1103/physrevlett.124.187002] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 03/02/2020] [Accepted: 04/14/2020] [Indexed: 06/11/2023]
Abstract
We use resonant inelastic x-ray scattering to investigate charge-stripe correlations in La_{1.675}Eu_{0.2}Sr_{0.125}CuO_{4}. 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 (La_{1.875}Ba_{0.125}CuO_{4}, La_{1.475}Nd_{0.4}Sr_{0.125}CuO_{4}, and La_{1.875}Sr_{0.125}CuO_{4}) 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 La_{1.675}Eu_{0.2}Sr_{0.125}CuO_{4} extend beyond the low-temperature tetragonal and pseudogap phase, their emergence heralds a spontaneous symmetry breaking in this compound.
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