Raman scattering in a two-layer antiferromagnet

Abstract

Two--magnon Raman scattering is a useful tool to verify recent suggestions concerning the value of the interplanar exchange constant in antiferromagnetic two--layer systems, such as $YB{a}_{2}C{u}_3{O}_{6+x}$. We present a theory for Raman scattering in a two--layer antiferromagnet. We study the spectra for the electronic and magnetic excitations across the charge transfer gap within the one--band Hubbard model and derive the matrix elements for the Raman scattering cross section in a diagrammatic formalism. We analyze the effect of the interlayer exchange coupling $J_2$ for the Raman spectra in $A_{1g}$ and $B_{1g}$ scattering geometries both in the non--resonant regime (when the Loudon--Fleury model is valid), and at resonance. We show that within the Loudon--Fleury approximation, a nonzero $J_2$ gives rise to a finite signal in $A_{1g}$ scattering geometry. Both, in this approximation and at resonance, the intensity in the $A_{1g}$ channel has a peak at {\it small} transferred frequency equal to twice the gap in the spin--wave spectrum. We compare our results with experiments in $YB{a}_{2}C{u}_3{O}_{6.1}$ and $S{r}_{2}Cu{O}_{2}C{l}_2$ compounds and argue that the large value of $J_2$ suggested in a number of recent studies is incompatible with Raman experiments in $A_{1g}$ geometry.

34 pages, Revtex file, 8 figures in a uuencoded, gziped tar file. The figures are also available upon request

References in corpus (7)

• Spin Gaps and Spin Dynamics in La_{2-x}Sr_xCuO_4 and YBa_2Cu_3O7_δ
• Phase Transition, Longitudinal Spin Fluctuations and Scaling in a Two-Layer Antiferromagnet
• Resonant two-magnon Raman scattering in parent compounds of high-T${}_c$ superconductors.
• Resonant two-magnon Raman scattering in antiferromagnetic insulators
• Spin Gaps and Bilayer Coupling in YBa${}_2$Cu${}_3$O${}_{7-\delta }$ and YBa${}_2$Cu${}_4$O${}_8$
• Spin pseudo-gap and interplane coupling in Y_2Ba_4Cu_7O_{15}: a ^{63}Cu nuclear spin-spin relaxation study
• Systematic 1/S study of the 2D Hubbard model at half-filling

Cited by in corpus (7)

• Inelastic Light Scattering From Correlated Electrons
• Using RIXS to uncover elementary charge and spin excitations in correlated materials
• Double-layer Heisenberg antiferromagnet at finite temperature: Brueckner Theory and Quantum Monte Carlo simulations
• Mid-infrared absorption in YBa2Cu3O6: Failure of spin-wave theory in undoped cuprates?
• Electronic Raman scattering in correlated materials: exact treatment of nonresonant, mixed, and resonant scattering with dynamical mean field theory
• Two-magnon Raman scattering from the Cu3O4 layers in (Sr,Ba)2Cu3O4Cl2
• Effect of next-nearest neighbor hopping on the spin dynamics in antiferromagnets