Plasmon‐Enhanced Photodetection in Ferromagnet/Nonmagnet Spin Thermoelectric Structures

Abstract

The photothermoelectric (PTE) effect that originates from the temperature difference within thermoelectric materials induced by light absorption can be used as the mechanism for a light sensor in optoelectronic applications. In this work, a PTE-based photodetector is reported using a spin thermoelectric structure consisting of CoFeB/Pt metallic bilayers and its signal enhancement achieved by incorporating a plasmonic structure consisting of Au nanorod arrays. The thermoelectric voltage of the bilayers markedly increases by 60 ± 10% when the plasmon resonance condition of the Au nanorods is matched to the wavelength of the incident laser. Full-wave electromagnetic simulations reveal that the signal enhancement is due to the increase in light absorption and consequential local heating. Moreover, the alignment of the Au nanorods makes the thermoelectric voltages sensitive to the polarization state of the laser, thereby enabling the detection of light polarization. These results demonstrate the feasibility of a hybrid device utilizing plasmonic and spin-thermoelectric effects as an efficient PTE-based photodetector.

Synergistic SERS Enhancement in GaN‐Ag Hybrid System toward Label‐Free and Multiplexed Detection of Antibiotics in Aqueous Solutions

“…Previous research using S‐nTP typically fabricated plasmonic nanostructures on a flat substrate. [ 9 , 17 ] However, due to the highly conformal printing capability of S‐nTP, we could fabricate Ag NWs with sub‐20 nm width on the top surface of GaN NPs (Figure 1d ). Another potential route for fabricating similar structures is to drop‐cast solution‐processed Ag NWs on GaN NPs.…”

Amplification of Spin Thermoelectric Signals in Multilayer Spin Thermopiles

“…Spin thermoelectrics, which is a thermoelectric effect in magnetic structures, takes advantage of the interconversion between heat, spin, and charge currents. − Also known as spin caloritronics, it is of great interest because it provides not only a novel scheme of generating spin current − but also an efficient means of energy harvesting from waste heat, mediated by spin current. − The spin Seebeck effect (SSE) is a typical spin thermoelectric phenomenon; an electrical voltage is generated in a ferromagnet (FM)/normal metal (NM) bilayer structure, in which a thermally induced spin current is injected from the FM into the NM and is subsequently converted to an electric voltage via inverse spin Hall effect (ISHE) in the NM layer with spin–orbit interaction. − Compared to conventional thermoelectrics, the spin thermoelectrics employing the SSE has the following advantages: first, independent control of electrical and thermal conductivities is possible because electrical voltage is produced along the FM/NM bilayer while a temperature gradient is applied in the direction perpendicular to the layer plane . This allows for materials engineering to optimize the thermoelectric figure of merit without constraint due to the Wiedemann–Franz law. ,,, Second, spin thermoelectrics facilitates a simple device structure of a thin film bilayer, offering a wide range of applicability, such as scalability to cover a large area and compatibility with any surface, including flexible substrates. − Due to these advantages, the spin thermoelectric effect is being actively investigated as a next-generation energy harvester or heat sensor. − , However, the power generation efficiency of the spin thermoelectric effect has to be much improved for actual applications.…”

“…17−19 Due to these advantages, the spin thermoelectric effect is being actively investigated as a next-generation energy harvester or heat sensor. [16][17][18][19][20]27 However, the power generation efficiency of the spin thermoelectric effect has to be much improved for actual applications.…”

Significantly Boosted Photothermoelectric Effect via Carrier Injection in Au Decorated SWCNT Films for Infrared Detection

“…For most photodetectors working on lightmodulated photoexcitation related physical processes, the PTE voltages are generally low. [16][17][18]20,[26][27][28][31][32][33] Although SrTiO 3 with large intrinsic Seebeck coefficient and phonon-enhanced pho- [8,[16][17][18][19][20][21] toresponse, its ultrahigh PTE voltages are generated under illumination of highly intense laser, with power density exceeding a hundred W cm −2 . [8] By contrast, combining photothermal and thermoelectric effects provides a promising approach to obtain high output performance and the crucial issue is to enhance the temperature difference built via photothermal effect.…”