Quantitative imaging of hybrid chiral spin textures in magnetic multilayer systems by Lorentz microscopy

Chiral magnetic textures in ultrathin perpendicularly magnetized multilayer film stacks with an interfacial Dzyaloshinskii-Moriya interaction have been the focus of much research recently. The chirality associated with the broken inversion symmetry at the interface between an ultrathin ferromagnetic layer and a heavy metal with large spin-orbit coupling supports homochiral N\'eel domain walls and hedgehog (N\'eel) skyrmions. Under spin-orbit torques these N\'eel-type magnetic structures are predicted, and have been measured, to move at high velocities. However recent studies have indicated that some multilayered systems may possess a more complex hybrid domain wall configuration, due to the competition between interfacial DMI and interlayer dipolar fields. These twisted textures are expected to have thickness dependent N\'eel and Bloch contributions to the domain or skyrmion walls. In this work, we use the methods of Lorentz microscopy to determine quantitatively experimentally both (i) the contributions of the N\'eel and Bloch components and (ii) their spatial spin variation at high resolution. These are compared with modeled and simulated structures that are in excellent agreement with our experimental results. Our quantitative analysis provides powerful direct evidence of the Bloch wall component which exists in these hybrid walls and will be significant when exploiting chirality in spintronic applications.