Longitudinal Magneto-Optical Kerr Effect of Nanoporous CoFeB and W/CoFeB/W Thin Films

Transverse magneto-optical behavior of nanoporous ferromagnetic film based on anodic aluminum oxide/aluminum template and its sensing application

The transverse magneto-optical Kerr effect (TMOKE) has attracted widespread scientific interest because of its potential applications in biosensor technology, data storage, optical isolation, and telecommunications. More conventional architectures, including prism-based metal/magnetic multilayers and nanoarrays that integrate plasmonic and magnetic materials, are commonly used to amplify TMOKE through the high-quality propagation of the surface plasmon resonance optical mode. However, the main disadvantages of these architectures are their large ohmic losses and radiation damping, resulting in a large optical spectrum linewidth, which hinders the sensing performance. Here, we use a theoretical approach to show that it is possible to employ a low-loss Fabry-Perot optical mode on a magneto-optical platform for TMOKE signal and gaseous sensing enhancement by means of a single CoFeB ferromagnetic film directly overlayed on an already industrial anodic aluminum oxide/aluminum template. The proposed strategy can therefore potentially be exploited for high-precision and low-loss magneto-optical sensors.

Silver Nanopillar Arrayed Thin Films with Highly Surface-Enhanced Raman Scattering for Ultrasensitive Detection

Surface-enhanced Raman scattering (SERS) technique based on surface plasmon resonance has been considerably investigated in recent years due to its superior sensitivity in the detection of organic or biological molecules at trace levels. However, most research usually focuses on artificial architectures as SERS substrates that always have a complex and expensive micro-nanofabrication process. The high cost of masks for SERS substrates becomes a key obstacle for the widespread commercialization of SERS technology. In this paper, a biomimetic SERS substrate composed of silver-coated nanopillar arrays on the top of a cicada wing was advanced to overcome these challenges as both substrates and masks. Benefiting from the high near-field plasmon resonance coupling at the limited space among neighboring nanopillars, a dramatically increased SERS signal can be achieved using rhodamine 6G (R6G) as a model molecule. Encouragingly, the analytical enhancement factor of the order of more than 10⁸ has been conveniently realized with a reliable detection concentration of R6G of about 100 pM or less. This work provides a promising route for designing cost-effective and highly sensitive SERS substrates and the related mask fabrication using our previously proposed template transfer nanoimprint.