Disorder effects upon the two-magnon Raman scattering spectrum in a Hubbard antiferromagnet

Two-magnon Raman scattering intensity is obtained for a two-dimensional (2D) spin-1/2 antiferromagnet in presence of hopping (off-diagonal) and on-site (diagonal) disorder. For hopping disorder it is seen that a minute amount of disorder leads to a substantial broadening of the Raman lineshape. Whereas the amount of on-site disorder needs to be sufficiently high to obtain any observable broadening in the Raman spectrum. In particular. it is shown that the broadening of the Raman lineshape for the hopping disorder case which arises from an asymmetric energy renormalisation in the magnon spectrum leads to a surprisingly good agreement with the experimentally obtained two-magnon Raman profile for the copper-oxide insulators such as La2CuO4.