OPTOMETAMAG - Optical-control of thermally driven magnetic phase transitions in metamaterials

Thermoplasmonics refers to the use of plasmonic nanoparticles as sources of heat remotely controlled by light. This recently emerged and continuously growing research field demonstrated a unique and versatile approach for the fast optical control of temperature and the generation of high-temperature gradients with a nanoscale spatial resolution. This unique ability to release heat on the nanoscale has already impacted a broad range of research activities, including nanomedicine, cell biology, photothermal and hot-electron chemistry, and solar light harvesting.

Its application to condensed matter physics and material science is still a highly uncharted terrain despite the potentially broad impact given the multitude of temperature-dependent phenomena under continuous scrutinization in both fundamental and applied studies. Specifically, only a few uses of thermoplasmonic heating in magnetism have been investigated. In our seminal works, we demonstrated the fast and remote control of the temperature of nanomagnets across their blocking and Curie temperatures. Subsequently, we proposed the fast, local, and selective heating of nanomagnets via optical degrees of freedom to implement a novel class of opto-nanomagnetic logic devices. However, often the temperature that should be reached to induce the desired magnetic transition is quite high using the conventional ferromagnetic materials utilized so far. Clearly, achieving a control of the temperature-induced magnetic transitions to overcome the limited available materials options, would make the impact of thermoplasmonic heating much broader. A promising class of metamaterials recently emerged that could be utilized instead of and beyond conventional magnetic materials are the nanoscale graded metamaterials . They are complex materials structures, with a graded concentration of materials, which have demonstrated the ability to generate a strongly temperature-dependent coupling of different layer segments. Most notably, such materials can be made with high precision, and they allow for a predesigned temperature dependence of magnetic properties, which can be dramatically changed via modest temperature variations. Therefore, the development of hybrid systems that combine the uniqueness of thermoplasmonic heating with such matamaterials displaying magnetic phenomena that change abruptly across precisely engineered critical temperatures will provide a unique ground for the exploration of the fundamental occurrence of phase transitions. Furthermore, such type of structures offers very powerful prospects for the occurrence of novel phenomena that can be activated with a moderate temperature increase, which open extraordinary prospects for ultra-low energy applications in the fields of magneto-calorics, spintronics, magnonics, and magnetic data storage and processing.

By fabricating hybrid plasmonic-metamagnetic devices combining advanced nanoscale graded materials synthesis and nanolithography methods, in this project, we plan to explore the advantages of optically reconfigurable thermal gradient engineering and targeted local heating via optical degrees of freedom to advance the understanding, design, and control of magnetic critical phenomena using graded materials. With our best of both worlds approach, we will also target the implementation of novel functionalities that are technologically attractive for ultra-low energy magneto-caloric, spintronics, and nanomagnetic logic applications.

This project is funded by PID2021-123943NB-I00/MCIN/ AEI /10.13039/501100011033/ y por FEDER Una manera de hacer Europa