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Collective nature of orbital excitations in layered cuprates in the absence of apical oxygens

DOI: 10.1103/PhysRevLett.132.066004 DOI Help

Authors: Leonardo Martinelli (Politecnico di Milano) , Krzysztof Wohlfeld (University of Warsaw) , Jonathan Pelliciari (National Synchrotron Light Source II, Brookhaven National Laboratory; Massachusetts Institute of Technology) , Riccardo Arpaia (Chalmers University of Technology) , Nicholas B. Brookes (ESRF-The European Synchrotron) , Daniele Di Castro (CNR-SPIN, Università di Roma Tor Vergata) , Mirian Garcia-Fernandez (Diamond Light Source) , Mingu Kang (Massachusetts Institute of Technology) , Yoshiharu Krockenberger (NTT Corporation) , Kurt Kummer (ESRF-The European Synchrotron) , Daniel E. Mcnally (Paul Scherrer Institut) , Eugenio Paris (Paul Scherrer Institut) , Thorsten Schmitt (Paul Scherrer Institut) , Hideki Yamamoto (NTT Corporation) , Andrew Walters (Diamond Light Source) , Ke-Jin Zhou (Diamond Light Source) , Lucio Braicovich (Politecnico di Milano; ESRF-The European Synchrotron) , Riccardo Comin (Massachusetts Institute of Technology) , Marco Moretti Sala (Politecnico di Milano) , Thomas P. Devereaux (Stanford Institute for Materials and Energy Sciences, SLAC; Stanford University) , Maria Daghofer (University of Stuttgart) , Giacomo Ghiringhelli (CNR-SPIN, Politecnico di Milano)
Co-authored by industrial partner: Yes

Type: Journal Paper
Journal: Physical Review Letters , VOL 132

State: Published (Approved)
Published: February 2024
Diamond Proposal Number(s): 20690

Abstract: We have investigated the 3 d 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 x y 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.

Journal Keywords: Exchange interaction; Quasiparticles & collective excitations; Cuprates; High-temperature superconductors; Strongly correlated systems; Exact diagonalization; Hubbard model; Resonant inelastic x-ray scattering

Subject Areas: Materials, Physics

Instruments: I21-Resonant Inelastic X-ray Scattering (RIXS)

Other Facilities: ID32 at ERSF

Added On: 14/02/2024 11:52

Discipline Tags:

Superconductors Quantum Materials Physics Hard condensed matter - structures Magnetism Materials Science

Technical Tags:

Scattering Resonant Inelastic X-ray Scattering (RIXS)