Effects of curvature and torsion on magnetic nanowires

Here, we consider theoretical description and fabrication of thin wires, which are arranged along space curves. Geometry of these nanoarchitectures is characterized by two functions: curvature and torsion, which determine the modification of magnetic responses. The torsion being the key distinguishing parameter from flat curvilinear wires (discussed in Chapter 1) is in the focus of this chapter. The presented analytical approach to address thin wires of circular cross-section (wires) and rectangular cross-section (thin ribbons) deals with the geometry-induced effects stemming from the symmetric and antisymmetric exchange, as well as symmetries of spin-orbit and spin-transfer torques. Using helix- and helicoid-based samples as a case study, we discuss fundamental features in magnetic textures of geometries with twists in three-dimensional space and compare properties of ferromagnetic samples with antiferromagnetic spin chains. The experimental techniques to develop and characterize ferromagnetic nanowires of arbitrary shape at the nanoscale are described.