Photo credit: www.sciencedaily.com
Advanced Method Offers High-Resolution Analysis of Magnetic Nanostructures
Researchers at Martin Luther University Halle-Wittenberg (MLU) and the Max Planck Institute of Microstructure Physics in Halle have introduced an innovative technique that significantly enhances the analysis of magnetic nanostructures. This method achieves an impressive resolution of approximately 70 nanometres, a considerable improvement over traditional light microscopes which typically have a resolution limit of around 500 nanometres. This advancement is particularly relevant for developing next-generation energy-efficient storage technologies that rely on spin electronics, as reported in the latest issue of the journal ACS Nano.
Standard optical microscopes are constrained by the wavelength of light, which hinders the resolution of features smaller than about 500 nanometres. The newly developed approach circumvents this limitation by employing the anomalous Nernst effect (ANE) alongside a metallic nano-scale tip. Professor Georg Woltersdorf from the Institute of Physics at MLU explains, “ANE produces an electrical voltage in a magnetic material that is perpendicular to both the magnetisation and a temperature gradient.” The technique involves a focused laser beam directing heat to the tip of a force microscope, creating a temperature gradient that is confined to nanoscale dimensions. This metallic tip functions akin to an antenna, concentrating the electromagnetic field in a minuscule region beneath its point, thus enabling ANE measurements with a resolution that surpasses that of traditional light microscopy.
Prior research primarily focused on examining magnetic polarization within the sample plane. However, the MLU team acknowledges that the in-plane temperature gradient is integral, allowing for the exploration of out-of-plane polarization through ANE measurements. To validate the effectiveness of the ANE technique in visualising magnetic structures at the nanoscale, the researchers employed a magnetic vortex structure in their experiments.
One notable advantage of this new methodology is its applicability to chiral antiferromagnetic materials. “Our discoveries are pivotal for thermoelectric imaging of spintronic devices, and we’ve already demonstrated this capability with chiral antiferromagnets,” notes Woltersdorf. He emphasizes that the method offers dual benefits: significantly enhanced spatial resolution of magnetic structures beyond the limits of optical techniques, and the ability to probe chiral antiferromagnetic systems. This aspect aligns with the objectives of the forthcoming Cluster of Excellence, ‘Centre for Chiral Electronics,’ for which MLU, in collaboration with Freie Universität Berlin, the University of Regensburg, and the Max Planck Institute of Microstructure Physics, is pursuing funding under Germany’s Excellence Strategy. The overarching goal is to establish foundational concepts for future electronics.
This research was supported by the German Research Foundation (DFG) and falls within the Collaborative Research Centre / Transregio (CRC TRR) 227, Project-1D 328545488.
Source
www.sciencedaily.com