Enhancement on spin thermoelectric voltage of CoFeB/Pt bilayer from Au and Ag localized surface plasmon resonance

Abstract

Surface plasmons are widely used in sensors and energy fields because they can localize and trap light, but the light energy absorbed in plasmon itself is generally considered to be a loss. Since the plasmon occurs in metal-based structure, the absorption of visible light is unavoidable. However, little research has been done to gather this heat into reusable form of energy. So, given this situation, a novel way of harvesting the omnipresent thermal energy from plasmonic structure can be beneficial, and in tandem with photovoltaic devices it is necessary for the sake of maximizing energy conversion from solar energy to electricity. This inspired us to explore the possibility of gathering discarded thermal energy from plasmon structure into useful electric energy by thermoelectric effect, and in this work, we have adopted a recently discovered effect, so-called the spin Seebeck effect from which ferromagnet/heavy metal bilayer can generates magneto-thermovoltage. With the aim mentioned above, on top of ferromagnetic CoFeB/nonmagnetic Pt metallic bilayer, we have transferred Au nanorod or Ag nanomesh plasmonic nanostructures by nanoimprint method and conducted thermoelectric measurement from the laser-induced heating. Upon resonance condition, the combined structure showed increase in the thermoelectric voltage compared to the structure without plasmonic structure. As a result, we have successively demonstrated that plasmon-induced heat can be used as additional heat source for the thermoelectric generation.