An antiferromagnetic layer of an insulator PrMn O3, CaMn O3, or Pr0.5 Ca0.5 Mn O3 has been sandwiched between two layers of ferromagnetic SrRu O3 on (001)-oriented SrTi O3 and LaAl O3 substrates using the pulsed laser deposition technique. Magnetotransport measurements reveal a change of anisotropy in the case of trilayers having a Pr0.5 Ca0.5 Mn O3 or a CaMn O3 spacer layer as compared to that of 20 unit cells thick film of SrRu O3, while in the case of PrMn O3 spacer layer, the change of anisotropy is negligible. In addition, two switching magnetic fields are observed with the trilayer made of PrMn O3 spacer layer in the field-dependent anisotropic magnetoresistance. The results are discussed using the concept of spin-orbit coupling and spin mixing conduction process at the interfaces. © 2007 The American Physical Society.