  Spin-related effects in thermoelectricity can be used to design more
efficient refrigerators and offer novel promising applications for the
harvesting of thermal energy. The key challenge is to design structural and
compositional magnetic material systems with sufficiently high efficiency and
power output for transforming thermal energy into electric energy and vice
versa. Here, the fabrication of large-area 3D interconnected Co/Cu nanowire
networks is demonstrated, thereby enabling the controlled Peltier cooling of
macroscopic electronic components with an external magnetic field. The
flexible, macroscopic devices overcome inherent limitations of nanoscale
magnetic structures due to insufficient power generation capability that limits
the heat management applications. From properly designed experiments, large
spin-dependent Seebeck and Peltier coefficients of $-9.4$ $\mu$V/K and $-2.8$
mV at room temperature, respectively. The resulting power factor of Co/Cu
nanowire networks at room temperature ($\sim7.5$ mW/K$^2$m) is larger than
those of state of the art thermoelectric materials, such as BiTe alloys and the
magneto-power factor ratio reaches about 100\% over a wide temperature range.
Validation of magnetic control of heat flow achieved by taking advantage of the
spin-dependent thermoelectric properties of flexible macroscopic nanowire
networks lay the groundwork to design shapeable thermoelectric coolers
exploiting the spin degree of freedom.
