Magnon Splitting Induced by Charge Transfer in the Three-Orbital Hubbard Model

Yao Wang, Edwin W. Huang, Brian Moritz, and Thomas P. Devereaux

Phys. Rev. Lett. 120, 246401 – Published 11 June 2018

Abstract

Understanding spin excitations and their connection to unconventional superconductivity have remained central issues since the discovery of cuprates. Direct measurement of the dynamical spin structure factor in the parent compounds can provide key information on important interactions relevant in the doped regime, and variations in the magnon dispersion have been linked closely to differences in crystal structure between families of cuprate compounds. Here, we elucidate the relationship between spin excitations and various controlling factors thought to be significant in high- $T_{c}$ materials by systematically evaluating the dynamical spin structure factor for the three-orbital Hubbard model, revealing differences in the spin dispersion along the Brillouin zone axis and the diagonal. Generally, we find that the absolute energy scale and momentum dependence of the excitations primarily are sensitive to the effective charge-transfer energy, while changes in the on-site Coulomb interactions have little effect on the details of the dispersion. In particular, our result highlights the splitting between spin excitations along the axial and diagonal directions in the Brillouin zone. This splitting decreases with increasing charge-transfer energy and correlates with changes in the apical oxygen position, and general structural variations, for different cuprate families.

Received 4 November 2017

DOI:https://doi.org/10.1103/PhysRevLett.120.246401

Physics Subject Headings (PhySH)

Magnons Spin density waves Spin fluctuations Spin waves Superconductivity

Charge-transfer insulators Unconventional superconductors

Neutron scattering Resonant inelastic x-ray scattering

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Yao Wang^1,2,*, Edwin W. Huang^1,3, Brian Moritz^1,4, and Thomas P. Devereaux^1,5,†

¹SLAC National Accelerator Laboratory, Stanford Institute for Materials and Energy Sciences, 2575 Sand Hill Road, Menlo Park, California 94025, USA
²Department of Applied Physics, Stanford University, Stanford, California 94305, USA and Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
³Department of Physics, Stanford University, Stanford, California 94305, USA
⁴Department of Physics and Astrophysics, University of North Dakota, Grand Forks, North Dakota 58202, USA
⁵Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA