Antiferromagnetic-Metal/Ferromagnetic-Metal Periodic Multilayers for On-Chip Thermoelectric Generation

Abstract

On-chip thermoelectric generation is of vital importance and is attracting wide attention as an option for implementing green microelectronics. We achieve temperature sensing and energy harvesting using the anomalous Nernst effect (ANE) in ${\mathrm{[IrMn/magnetic metal]}}_{n}$ multilayers, which can be used as on-chip temperature sensors and thermoelectric generators. An increase of 103% (1356%) in the voltage (power) generation coefficient is achieved by increasing the number of periods ($n$) from 1 to 7, due to the enhanced interfacial spin-orbit-coupled scattering. The voltage and power generation coefficients of an optimized ${\mathrm{[IrMn/NiFe]}}_{5}$ sample with geometric dimensions of $1800\phantom{\rule{0.2em}{0ex}}\ensuremath{\mu}\mathrm{m}\ifmmode\times\else\texttimes\fi{}120\phantom{\rule{0.2em}{0ex}}\ensuremath{\mu}\mathrm{m}$ reach $1.3\phantom{\rule{0.2em}{0ex}}\ensuremath{\mu}\mathrm{V}\phantom{\rule{0.2em}{0ex}}{\mathrm{K}}^{\ensuremath{-}1}$ and $1.7\phantom{\rule{0.2em}{0ex}}\mathrm{pW}\phantom{\rule{0.2em}{0ex}}{\mathrm{K}}^{\ensuremath{-}2}$, respectively. Meanwhile, the exchange bias field introduced by Ir-Mn enables an ANE voltage and power output without an external field. Both features can advance the thermopower applications of ${\mathrm{[IrMn/magnetic metal]}}_{n}$ multilayers, especially the ${\mathrm{[IrMn/NiFe]}}_{n}$ system, for energy-efficient microelectronics.