Strain-controlled domain wall injection into nanowires for sensor applications

We investigate experimentally the effects of externally applied strain on injection 180$^\circ$ domain walls (DW) from a nucleation pad into magnetic nanowires, as typically used for DW-based sensors. In our study strain, generated by substrate bending, induces in material uniaxial anisotropy due to magnetoelastic coupling. To compare effects, $Co_{40}Fe_{40}B_{20}$, $Ni$ and $Ni_{82}Fe_{18}$ samples with in-plane magnetization different coupling are deposited. these samples, we measure field required DW, imaging differential contrast magneto-optical Kerr microscope. find that increases DW field, however, switching mechanism depends strongly direction respect wire axis. observe low facilitates creation wall at junction between wire, whereas strain-induced easy axis significantly coercive pad. Additionally, mechanical can be counteracted perpendicular show this induced annealing field. perform micromagnetic simulations support interpretation experimental findings. Our above described observations explained effective device. The influences well pinning entrance. As is key operation sensor performances, imposing lower limit operating window.