surfaces and their exchange-biased heterostructures from first principles*

We provide a complete and systematic first-principles study on the thermodynamic stability, structural parameters, and magnetic properties of the T1 non-collinear antiferromagnetic L1₂-IrMn₃ surface and exchange-biased L1₂-IrMn₃/Fe heterostructure. We find two stable surface and heterostructure terminations, which are in good agreement with experimental HR-TEM data. Using a comparative approach, we analyzed the exchange-bias properties in the heterostructure, discovering that the number of Mn-Fe interactions at the interface is related to exchange bias intensity. This finding could lead to novel exchange-bias tailoring by controlling the terminating layers. Finally, we describe the interface magnetic coupling atom-by-atom, finding a relationship between antiferromagnetic order near the interface, and heterostructure stability. Our analysis uncovers a possible mechanism for the appearance of exchange bias in non-collinear/collinear heterostructures. These results are in good agreement with hysteresis measurements of the IrMn₃/Fe bilayer.