Spin reorientation transition in the incommensurate stripe-ordered phase   of La3/2Sr1/2NiO4
  The spin ordering of La3/2Sr1/2NiO4 was investigated by magnetization measurements, and by unpolarized- and polarized-neutron diffraction. Spin ordering with an incommensurability epsilon ~ 0.445 is observed below T_so ~ 80 K. On cooling, a spin reorientation is observed at 57 +/- 1 K, with the spin axes rotating from 52 +/- 4 degrees to 78 +/- 3 degrees. This is the first time a spin reorientation has been observed in a La2-xSrxNiO4+delta compound having incommensurate stripe order. 
P.G. Freeman, A.T. boothroyd, D. Prabhakaran, D. Gonzalez, M. Enderle