Coupling between dynamic magnetic and charge-order correlations in the cuprate superconductor Nd2−xCexCuO4

Abstract

Charge order has now been observed in several cuprate high-temperature superconductors. We report a resonant inelastic x-ray scattering experiment on the electron-doped cuprate Nd2−xCexCuO4 that demonstrates the existence of dynamic correlations at the charge order wave vector. Upon cooling we observe a softening in the electronic response, which has been predicted to occur for a d-wave charge order in electron-doped cuprates. At low temperatures, the energy range of these excitations coincides with that of the dispersive magnetic modes known as paramagnons. Furthermore, measurements where the polarization of the scattered photon is resolved indicate that the dynamic response at the charge order wave vector primarily involves spin-flip excitations. Overall, our findings indicate a coupling between dynamic magnetic and charge-order correlations in the cuprates.

Doping dependence of d -wave bond-charge excitations in electron-doped cuprates

“…A possibility of d-wave bond-charge order 31 as well as the nematic order [36][37][38][39] is already discussed in h-cuprates. Therefore it is a crucial step toward the understanding of the charge dynamics in cuprates to clarify to what extent our results capture recent RXS data in e-cuprates [23][24][25] The peak width of S(q) shown in Fig. 3(a) is much larger than the experimental one 24 .…”

“…In Ref. 25, the spectral weight related to the CO signal is discussed to come from energy below 60 meV, whereas our sharp peak is realized in Fig. 5(a) for ω c ≈ 0.05 − 0.1, which corresponds to 50 -100 meV.…”

“…The understanding of the origin of those charge correlations, therefore, will likely yield an important clue to the origin of the pseudogap as well as high-T c superconductivity 12 . In fact, a large number of theoretical studies were performed 13-22 , although a consensus has not been obtained.On the other hand, a short-range CO was also observed in electron-doped cuprates [23][24][25] (e-cuprates). Since the pseudogap features similar to those in h-cuprates are much weaker in e-cuprates, a theoretical study may be less complicated in e-cuprates.…”

Formation of Incommensurate Charge Density Waves in Cuprates

“…This strongly points towards models in which CDW order is driven by local real-space correlations. Similar short-ranged CDW correlations that persist even to room temperature were recently observed in YBa 2 Cu 3 O 6+δ (YBCO) [18,37], Bi 2 Sr 2 CaCu 2 O 8+δ (Bi2212) [22], La 2−x Sr x CuO 4 (LSCO) [14,38] and electron doped Nd 2−x Ce x CuO 4 [39], strongly indicating an ubiquitous pCDW phase in underdoped cuprates. Our results are also compatible with previous STM studies of various cuprate families with- out magnetic stripe order at low temperature, such as Bi2212 and Ca 2−x Na x CuO 2 Cl 2 , where CDWs are found to be locally commensurate with large phase slips [40][41][42].…”

Adiabatic variation of the charge density wave phase diagram in the 123 cuprate (CaxLa1−x)(Ba1.75−xBluschke1, Yaari2, Schierle3 et al. 2019Phys. Rev. BSelf Cite14090View full textAdd to dashboardCite

“…Both theoretical and experimental results have supported the notion of a coupling between CDW order and antiferromagnetic fluctuations. 18,19,52,53 Various theoretical works 19,54 identified an emergent low-energy SU(2) symmetry relating d-wave superconductivity (particleparticle pairing) to charge ordering (particle-hole pairing), and the combined order parameter was shown to arise in the vicinity of an antiferromagnetic quantum critical point. 19 However, in our study the strongest CDW correlations are observed in the family with the weakest antiferromagnetism immediately calling into question whether CDW order could arise from antiferromagnetic quantum critical fluctuations.…”