Antiferromagnetic Domain Wall Manipulation and Measurement in Chromium Films

Antiferromagnets are described by their local magnetization as well as how this magnetization evolves with position. This contrasts with ferromagnets, which can be described by their magnetization vector alone. This feature adds an extra layer of complexity and richness to antiferromagnetic domain walls. Learning how these domain walls form, move, and affect electron transport is at the heart of understanding many intrinsic properties of antiferromagnetic materials. Precise measurements require domain walls of known shape and geometry that are pinned spatially and temporally to a specific nucleation site. By utilizing surface pinning and magnetic frustration effects, it is possible to lithographically pattern individual antiferromagnetic spin-density wave (SDW) domain walls in epitaxial Cr(001)/Fe/Au films on MgO(001). The creation of SDW domain walls is verified with x-ray microdiffraction and their location is confirmed with x-ray microfluorescence. Several devices, each containing a single lithographically patterned antiferromagnetic domain wall, are used to collect electrical transport data. From this data, one can isolate the resistance of an individual antiferromagnetic domain wall across the entire temperature range of the SDW order parameter. The domain wall resistivity shows an unexpected temperature dependence that helps to understand the possible mechanisms responsible for electron scattering in individual SDW domain walls.