Creating multi-layered thin films with alternating dissimilar sublayers is proposing unusual (electric, thermal, optical, etc.) properties to be experimentally investigated. In such a system where grain size and texture can be controlled by the deposition/annealing process represents a unique opportunity to focus on some aspects of the deformation processes driven by the collective behaviour of dislocation. Our aim was to create a system with large enough grains (500-800 nm in diameter) and engineer flat grain boundaries to study plastic deformation modified by the presence of barriers.

A hybrid thin film deposition system was used (Swiss Cluster) to create the samples by combining atomic layer deposition (ALD) and physical vapour deposition (PVD). Sequential deposition of $\sim 1 \mu$m thick multilayers were separated by 10 nm thick Al$_2$O$_3$ interlayers. The initial 100-250 nm grain size was increased by extensive heat treatment (at 800$^{\circ}$C for 4h under Ar atmosphere). Such final specimen was quite challenging to create without porosities or major delamination from the substrate after heat treatment.

Afterwards, micropillars were fabricated using focused ion beam (FIB) milling close to the edge of the bulk sample. These micropillars were then compressed at various strain rates (0.1-1000/s) using a nanodeformation setup (Alemnis AG). High (angular) resolution electron backscatter diffraction (HR-EBSD) was applied to study the geometrically necessary dislocation (GND) density distribution after low and high strain rate deformations. Sequential FIB-slicing was applied to create 3D reconstructions of the deformed volumes.