  We report an investigation of temperature and IrMn layered thickness
dependence of anomalous-Hall resistance (AHR), anisotropic magnetoresistance
(AMR), and magnetization on Pt/Ir20Mn80/Y3Fe5O12 (Pt/IrMn/YIG)
heterostructures. The magnitude of AHR is dramatically enhanced compared with
Pt/YIG bilayers. The enhancement is much more profound at higher temperatures
and peaks at the IrMn thickness of 3 nm. The observed spin-Hall
magnetoresistance (SMR) in the temperature range of 10-300 K indicates that the
spin current generated in the Pt layer can penetrate the entire thickness of
the IrMn layer to interact with the YIG layer. The lack of conventional
anisotropic magnetoresistance (CAMR) implies that the insertion of the IrMn
layer between Pt and YIG efficiently suppresses the magnetic proximity effect
(MPE) on induced Pt moments by YIG. Our results suggest that the dual roles of
the InMn insertion in Pt/IrMn/YIG heterostructures are to block the MPE and to
transport the spin current between Pt and YIG layers. We discuss possible
mechanisms for the enhanced AHR.
