Speaker
Description
In this contribution we introduce a novel approach for fabrication of magneto-resistive multilayer nanowires and present their spin structure determination using synchrotron radiation.
Complex nano-structuring routines on magnetic multilayers are frequently applied in data storage and sensor technology to functionalize devices via shape anisotropy. Here we test, if sputter deposition onto nano-facetted surfaces can be applied to form self-assembled, high-quality nanowires with adjustable size and extreme shape anisotropy. Fe/Cr superlattices with intended antiferromagnetic order were deposited in sequences of defined oblique orientation onto a nano-facetted Al$_2$O$_3$ wafer in which the facet morphology was adjusted via high-T annealing [1]. Due to a shadowing effect, well separated magneto-resistive nanowires are formed. A precise nanoscopic characterization, however, is challenging with lab-based techniques. To investigate the structural quality and magnetic properties of the wires we perform conventional as well as nuclear resonant grazing incidence small angle x-ray scattering [2]. While conventional GISAXS is used to extract the relevant parameters of the multilayer morphology, nuclear GISAXS at the $14.41$keV resonance of iron is applied to determine the field-dependent spin structure in the nanowires. These elegant ways for flexible multilayer nanowire formation and novel characterization are highly interesting for potential sensor and device applications requiring tunable magnetic anisotropies.
In this lecture we also discuss experimental conditions, advantages and challenges for similar experiments at a free electron laser.
References
[1] D. J. Erb et al., “Real-Time Observation of Temperature-Induced Surface Nanofaceting in M-Plane α-Al2O3,” ACS Applied Materials & Interfaces, vol. 14, no. 27. American Chemical Society (ACS), pp. 31373–31384, Jun. 28, 2022. https://doi.org/10.1021/acsami.1c22029
[2] D. Erb et al., “Disentangling magnetic order on nanostructured surfaces,” Physical Review Materials, vol. 1, no. 2. American Physical Society (APS), Jul. 17, 2017. https://doi.org/10.1103/physrevmaterials.1.023001
