Fractional spin excitations in the infinite-layer cuprate CaCuO${}_2$

Abstract

We use resonant inelastic x-ray scattering (RIXS) to investigate the magnetic dynamics of the infinite-layer cuprate CaCuO2. We find that close to the (1/2,0) point the single magnon decays into a broad continuum of excitations accounting for 80% of the total magnetic spectral weight. Polarization resolved RIXS spectra reveal the overwhelming dominance of spin-flip ($\Delta S=1$) characterof this continuum with respect to the $\Delta S=0$ multimagnon contributions. Moreover, its incident energy dependence is identical to that of the magnon, supporting a common physical origin. We propose that the continuum originates from the decay of the magnon into spinon pairs, and we relate it to the exceptionally high ring exchange $J_{\mathrm{c}}\sim J_1$ of CaCuO2. In the infinite layer cuprates long-range and multi-site hopping integrals are pivotal and amplify the 2D quantum magnetism effects in spite the 3D antiferromagnetic Néel order.

10 pages, 6 figures

References in corpus (16)

• Evidence for deconfined quantum criticality in a two-dimensional Heisenberg model with four-spin interactions
• Spin-Orbital Separation in the quasi 1D Mott-insulator Sr2CuO3
• Fractional excitations in the square-lattice quantum antiferromagnet
• Anomalous High-Energy Spin Excitations in La2CuO4
• Quantum dynamics and entanglement of spins on a square lattice
• Nearly deconfined spinon excitations in the square-lattice spin-1/2 Heisenberg antiferromagnet
• Hierarchical mean-field approach to the $J_1$-$J_2$ Heisenberg model on a square lattice
• Experimental Determination of Momentum-Resolved Electron-Phonon Coupling
• Low energy theory of the t-t'-t''-U Hubbard Model at half-filling: interaction strengths in cuprate superconductors and an effective spin-only description of La_2CuO_4
• The simultaneous measurement of energy and linear polarization of the scattered radiation in resonant inelastic soft x-ray scattering
• Polarization resolved Cu $L_3$-edge resonant inelastic x-ray scattering of orbital and spin excitations in NdBa${}_2$Cu${}_3$O${}_{7-\delta }$
• High Tc superconductivity at the interface between the CaCuO2 and SrTiO3 insulating oxides
• Level spectroscopy in a two-dimensional quantum magnet: Linearly dispersing spinons at the deconfined quantum critical point
• Multiple-magnon excitations shape the spin spectrum of cuprate parent compounds
• Exact diagonalization study of the Hubbard-parametrized four-spin ring exchange model on a square lattice
• Mobile orbitons in Ca${}_2$CuO${}_3$: crucial role of the Hund's exchange

Cited by in corpus (13)

• Exploring Quantum Materials with Resonant Inelastic X-Ray Scattering
• Emergence of spinons in layered trimer iridate Ba4Ir3O10
• Collective nature of orbital excitations in layered cuprates in the absence of apical oxygens
• Single- and Multimagnon Dynamics in Antiferromagnetic $\alpha$-Fe${}_2$O${}_3$ Thin Films
• Low temperature magnetism of KAgF3
• Magnon Spectra of Cuprates beyond Spin Wave Theory
• Softening of $dd$ excitation in the resonant inelastic x-ray scattering spectra as a signature of Hund's coupling in nickelates
• Theoretical analysis of multi-magnon excitations in resonant inelastic x-ray scattering spectra of two-dimensional antiferromagnets
• Observation of spin-conserving two-spinon continuum in the $S$=1/2 antiferromagnetic chain system Sr${}_2$CuO${}_3$ using Cu $K$-edge resonant inelastic x-ray scattering
• A light-induced charge order mode in a metastable cuprate ladder
• Exact results for the Hubbard model on bipartite lattices in spatial dimensions $d>1$: Seven theorems from the full [SU(2)$\times$SU(2)$\times$U(1)]/${\mathbb{Z}}_2^2$ symmetry
• Evaluating covalency using RIXS spectral weights: Silver fluorides vs. cuprates
• Multimagnon and multispinon $L_3$-edge RIXS spectra of an effective ${\tilde{J}}_1-{\tilde{J}}_2-{\tilde{J}}_3$ square lattice Heisenberg model