Strain-driven domain wall network with chiral junctions in an antiferromagnet.

Antiferromagnetic materials have recently emerged as promising candidates in spintronics. At the same time, more complex localized non-coplanar magnetic states such as skyrmions are in the research focus due to their intriguing dynamical and transport properties. Recently, a conceptual shift has occurred to envision the use of such magnetic defects not only in one-dimensional race track devices but also to exploit their unique properties in two-dimensional networks. Here we use local strain in a collinear antiferromagnetic film to induce a complex domain wall network. Using spin-polarized scanning tunneling microscopy we characterize the different building blocks of the network - ranging from collinear magnetic domains, over non-collinear domain walls, to non-coplanar localized domain wall junctions - on the atomic scale. We find that the triple domain wall junctions exhibit a structural handedness. The origin is an exchange-driven lateral relaxation as explained using first-principles calculations. We predict that the domain wall junctions exhibit topological orbital magnetization generated by their non-coplanar spin structure, implying topological transport properties due to the network.