Spin stripe fluctuations in antiferromagnetic Pr2-xSrxNiO4+d

Abstract

We report inelastic neutron scattering study of the antiferromagnetic spin stripe fluctuations above the spin stripe melting temperature Tso˜190K in the hole doped Pr2-xSrxNiO4+d with stripe incommensurability ?=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 Tso, while they are strongly diminished already below the charge stripe melting temperature Tco˜255K, 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.