Room-Temperature Exchange Bias and Training Effect in Co/IrMn₃ Thin Films with Varying Co Layer Thicknesses

We investigated room-temperature exchange bias phenomenon and training effect in SiO₂/Ru(40 ㎚)/Co(t ㎚)/IrMn3(5 ㎚)/Ta(5 ㎚) with varying Co layer thicknesses t = 2, 3, 5, 8, 10, and 20 ㎚. Consecutive hysteresis loop measurements by longitudinal magneto-optical Kerr effect (L-MOKE) revealed the presence of both athermal and thermal training effects in the Co/IrMn₃ ferromagnetic/antiferromagnetic bilayers. The athermal training effect is more prominent as the Co layer thickness increased. We also observed that the training effect constant γ increased with increasing Co layer thickness, suggesting that thicker samples were closer to equilibrium, as interpreted by Binek’s relaxation model. This study not only advances our understanding of the exchange bias phenomenon and training effect in the Co/IrMn₃ system but also may offer their potential for use in neuromorphic devices.