Magnetic correlations in La2-xSrxCoO4 studied by neutron scattering: possible evidence for stripe phases.

Spin correlations in La 2-x Sr x CoO 4 (0.3 ≤ x ≤ 0.6) have been studied by neutron scattering. The commensurate antiferromagnetic order of La 2 CoO 4 persists in a very short range up to a Sr content of x = 0.3, whereas small amounts of Sr suppress commensurate antiferromagnetism in cuprates and in nickelates. La 2-x Sr x CoO 4 with x > 0.3 exhibits incommensurate spin ordering with the modulation closely following the amount of doping. These incommensurate phases strongly resemble the stripe phases observed in cuprates and nickelates, but incommensurate magnetic ordering appears only at larger Sr content in the cobaltates due to a reduced charge mobility.