Serene Pauly (She/Her)

 

Current research project

Direct nanoscale mapping of plasmonic heating in nanostructures for HAMR

One of the key focus of CDT-PIADS is the development of plasmonics-mediated heating for magnetic recording which is expected to play crucial role in heat-assisted magnetic recording (HAMR). The topic has been explored from different perspectives such as materials development, plasmonic response and arising thermal effects. These aspects have been studied separately and macroscopic measurements have been used to connect the dots for what appears to be a nanoscale phenomena (especially in the context of nanostructures being employed for plasmonic heating). Is it possible to combine the different strands of the problem together and develop an approach that allows direct visualisation of plasmocs-mediated thermal transport on the nanoscale? As has been highlighted in several current publications[1], one of the main challenges in the field of thermal plasmonics is the need to directly measure light- induced heat with nanoscale resolution. This project aims to address this key issue by combining nanoscale scanning thermal miscroscopy with laser enabled plasmonic excitation on materials and nanostructures of prime interest for HAMR. The project will rely on the key expertise of three members of staff at QUB : Dr. A. Kumar (expertise in photoconductive AFM and Scanning Thermal microscopy), Dr. F Huang (expertise in plasmonics) and Dr. R. McQuaid (expertise in thermal transport). Our team has recently developed photoconductive AFM (a running CDT project with Nathan Black) and tuned the instrument for wavelength selectivity. The geometry automatically facilitates plasmonic heating along with wavelength selectivity from the Laser source. As part of parallel CDT project led by Rebecca Kelly (supervised by Dr. McQuaid), we have tuned the sensitivity of scanning thermal microscopy[2] to 10 mK which represents one of the most sensitive probes of temperature with 10-nm spatial resolution. These developments offer the key prospect of merging the approaches together to enable direct nanoscale mapping of plasmonic heating in metallic nanostructures. With the above context, The project will combine the different elements of thermal plasmonics by developing an experiment methodology that directly combines the light-mediated plasmonic heating in nanostructures with scanning thermal microscopy. The experiments will be combined with COMSOL-based simulation of the plasmonic as well as thermal response to develop a predictive framework for materials of interest. The materials for this study will be chosen from two families : (a) conventional deposited thin films (Au, Pt, TiN etc.) and fabricated nanostructures (FIB nanostructures, nanorods, selected geometries); and (b) Metal nanoparticles on 2D materials with plasmonic coupling. The results will focus on the arising temperatures in chosen material systems as a function of selected wavelength, light intensity. We will also aim to investigate the role of interfaces (grain boundaries, defects) in mediating the spatially resolved thermal response. The role of thermal diffusion in mediating the plasmonic heating response will also be assessed. The nanoscale experiments will be combined with macroscopic measurements to then develop a holistic perspective on how the plasmonic heating can be best optimised for HAMR applications. The capacity to measure temperature distribution of plasmonic structures at the nanoscale should also be useful for thermal plasmonic applications such as thermal photovoltaics, nanochemistry and nanolithography.