Phonons and magnons in stripe-ordered nickelates. A Raman scattering study

Abstract

Electronic correlation effects in La₂-xSrxNiO₄ (x = 1/3 and 0.225) lead to spontaneous phase separation into microscopic spin/charge stripes with commensurate and incommensurate order, respectively. Raman scattering experiments on such single crystalline materials show a rich phenomenology of phonon and magnon anomalies due to the new, self-organized periodicities. These effects are observable as function of temperature but can also be induced by cooling in a seemingly small magnetic field leading to a reorganization of stripe structure.