Direct device integration of single 1D nanoparticle assemblies; a magnetization reversal and magnetotransport study

Nanochains (NCs) made up of a one-dimensional arrangement of magnetic nanoparticles (NPs) exhibit anisotropic properties with potential for various applications. Herein, using a novel self-assembly method we directly integrate single NCs onto desired substrates including devices. We present a nanoscopic analysis of magnetization reversal in 1D linear NP arrays by combining x-ray microscopy, magnetoresistance (MR), and micromagnetic simulations. Imaging the local magnetization along individual NCs by scanning transmission x-ray microscopy and x-ray magnetic circular dichroism under varyingin situmagnetic fields shows that each structure undergoes distinct non-homogeneous magnetization reversal processes. The experimental observations are complemented by micromagnetic simulations, revealing that morphological inhomogeneities critically influence the reversal process where regions with parallel chains or larger multi-domain particles act as nucleation centers for the magnetization switching and smaller particles provide pinning sites for the domain propagation. Magnetotransport through single NCs reveals distinct MR behavior that is correlated with the unique magnetization reversal processes dictated by the morphology of the structures. This study provides new insights into the complex magnetization reversal mechanism inherent to one-dimensional particle assemblies and the effective parameters that govern the process.