  Although spin injection at room temperature in an IrMn metallic
antiferromagnet strongly depends on the transport regime, and is more efficient
in the case of magnonic transport, in this article, we present experimental
data demonstrating that the enhanced efficiency of spin injection caused by
spin fluctuations near the ordering temperature can be as efficient for the
electronic and magnonic transport regimes. By selecting representative
interacting environments, we also demonstrated that the amplification of spin
injection near the ordering temperature of the IrMn antiferromagnet is
independent of exchange coupling with an adjacent NiFe ferromagnet. In
addition, our findings confirm that the spin current carried by magnons
penetrates deeper than that transported by conduction electrons in IrMn.
Finally, our data indicates that the value of the ordering temperature for the
IrMn antiferromagnet is not significantly affected by either the electronic or
magnonic nature of the spin current probe, or by exchange coupling.
