Exchange coupling at the interface of antiferromagnet and rare-earth bilayers

Helical or non-collinear structures in rare-earth (RE) when topologically stable, can form the basis of realizing all-spin-based technology. Strong coupling at the ferromagnet (FM)-RE interface, reported earlier, originates from the number of irreversible spins owing to the imbalance in the non-collinear configuration within the RE layer. Here, we explore the exchange coupling between an antiferromagnet (AF) and a rare-earth (RE) i.e. within Mn3Ir//Dy bilayers for two different Dy thicknesses. A frustrated inter-domain magnetic interaction at the exchange-coupled interfaces of AF-RE specimen with the thicker Dy layer leads to a coexistence of spin-freezing like ordering around the temperature range where the helical spin configuration is expected to be established. Due to the small number of irreversible spins within the RE, the corresponding interfacial coupling around the temperature range of the helical phase remains weak leading to minimal exchange bias field irrespective of the Dy thickness.