Spin stripe fluctuations in antiferromagnetic Pr 2 − x Sr x NiO 4 + δ

We report inelastic neutron scattering study of the antiferromagnetic spin stripe fluctuations above the spin stripe melting temperature T-so approximate to 190 K in the hole doped Pr2-xSrxNiO4+delta with stripe incommensurability is an element of = 0.33. The fluctuations are nondispersive and detected upto 10 meV at the incommensurate wave vector indicating a persisting instantaneous spin and charge stripe correlation above T-so, while they are strongly diminished already below the charge stripe melting temperature T-co approximate to 255 K, which indicates that static charge stripe order is essential for the dynamical spin stripe correlation to exist. Furthermore, it also suggests that the presence of spin stripe fluctuations is not a prerequisite for the formation of static charge stripes.