Geometrically designed domain wall trap in tri-segmented nickel magnetic nanowires for spintronics devices

[EN] “Domain wall traps” have been engineered and well-exploited in nanostrips by creating a geometrical trapping site, e.g. a single notch along a stripe, compared to diameter-modulated (DM) cylindrical magnetic nanowires (NWs) where multi-segmented DM-NWs have been generally studied. Here, we report our systematic study on the magnetization behavior, domain wall structure and its nucleation/propagation in tri-segmented diameter-modulated Ni nanowires, a simple system to investigate the magnetization reversal as function of segment geometry and lay-out order. We find out that the magnetization behavior of single Ni DM-NWs exhibits the significance of positional ordering of thick and thin segments, distinguished by two distinct geometries including: dumbbell-type (type I) and rolling pin-type (type II). Based on experimental and theoretical simulations, it was evidenced that the wide-narrow junctions create trap sites for domain walls where the narrow segment restricts their motion. This type of geometrically engineered nanowires exhibit potential efficiency for future novel spintronic devices in particular when assembled in arrays of DM-NWs as a practical three-dimensional memory device.The financial support of Iranian National Science Foundation (INSF) under a grant number of 94010670 is acknowledged. F.N. acknowledges the financial support of CSIC to visit ICMM at Madrid. S.M.P. acknowledges the visiting scholarship to ICMM from Iranian Ministry of Science, Research and Technology and Sahand University research affair’s research studentship grant. Authors wish to thank Agustina Asenjo from ICMM/CSIC for her support in the MFM imaging and interpretation. This work has been partly supported by the Spanish Ministry of Economy, Industry and Competitiveness (MINECO) under project MAT2016-76824-C3-1-R and by the Regional Government of Madrid under project S2018/NMT-4321 NANOMAGCOST-CM. A.P. is co-financed by Greece and the European Union (European Social Fund ESF) through the Operational Programme «Human Resources Development, Education and Lifelong Learning» in the context of the project “Strengthening Human Resources Research Potential via Doctorate Research” (MIS-5000432), implemented by the State Scholarships Foundation (ΙΚΥ). DK acknowledges financial support from the Special Account for Research of ASPETE through project NANOSKY (No 80146)