Dual structure in the charge excitation spectrum of electron- doped cuprates

YAMASE, HIROYUKI; BEJAS, MATÍAS; GRECO, ANDRÉS

Sendai

Workshop; Research Frontier of Advanced Spectroscopies for Correlated Electron Systems; 2019

Institute for Materials Research (IMR), Tohoku University, Sendai, Japan

For electron-doped cuprates, charge order and high-energy charge excitations are observed by resonant x-ray scattering (RXS) [1,2] and resonant inelastic x-ray scattering (RIXS) [3,4,5], respectively. Motivated by these experiments, we study the charge excitation spectrum of the layered t-J model with long-range Coulomb interaction [6]. We findthat the charge excitation spectrum is characterized by a dual structure in energy space. Bond-charge fluctuations driven by the exchange term (J term) are responsible for the low-energy excitations, whereas the high-energy spectrum is dominated by usual on-site charge fluctuations, which yield plasmon excitations above the particle-hole continuum.We discuss that the charge order observed by RXS [1,2] can be bond-charge order characterized by d-wave symmetry [7, 8] and the RIXS spectrum around in-plane momentum (0,0) [3,4,5] can correspond to plasmons [9, 10].1) E. H. da Silva Neto et al., Science 347, 282 (2015).2) E. H. da Silva Neto et al., Sci. Adv. 2, 1600782 (2016).3) W. S. Lee et al., Nat. Phys. 10, 883 (2014).4) K. Ishii et al., Nat. Commun. 5, 3714 (2014).5) M. Hepting et al., Nature 563, 374378 (2018).6) M. Bejas, H. Yamase, and A. Greco, Phys. Rev. B 96, 214513 (2017).7) H. Yamase, M. Bejas, and A. Greco EPL, 111 57005 (2015).8) H. Yamase, M. Bejas, and A. Greco, Phys. Rev. B 99, 014513 (2019).9) A. Greco, H. Yamase, and M. Bejas, Phys. Rev. B 94, 075139 (2016).10) A. Greco, H. Yamase, and M. Bejas, Commun.Phys. 2, 3 (2019).