MnP films with desired magnetic, magnetocaloric and thermoelectric properties for a perspective magneto-thermo-electric cooling device

TL;DR

This paper demonstrates that MnP nanorod films with specific magnetic, magnetocaloric, and thermoelectric properties are promising for magneto-thermo-electric cooling devices, showing potential for high-frequency operation.

Contribution

It introduces MnP nanorod films with optimized properties suitable for MTECDs, highlighting their growth, characterization, and potential application in cooling devices.

Findings

Achieved a large power factor of 24.06 μW m-1 K-2 at room temperature.

Demonstrated small magnetocaloric effect with -deltaSM ~0.64 J/kg K.

Films exhibit ferromagnetism enhancing magnetocaloric properties.

Abstract

A perspective magneto-thermo-electric cooling device (MTECD) comprising a central magnetocaloric (MC) material (e.g., Gd) sandwiched by two thermoelectric (TE) materials (e.g., MnP) is proposed. The presence of the TE materials in the MTECD guides the heat flow direction and enhances heat pulsation. In this case, the usage of a ferromagnetic TE material that combines large TE with small MC properties within a similar temperature region can enhance the magnetic flux density and heat exchange efficiency. Here, we show that MnP nanorod-structured films with desired magnetic, MC and TE properties are very promising for use in MTECDs. The films were grown on Si substrates at 300, 400 and 500{\deg}C using molecular beam epitaxy. The 400 oC sample shows a desired TE and MC combination. A large power factor of 24.06 {\mu}W m-1 K-2 is achieved at room temperature. In this temperature region, the film exhibits a small MC effect (-deltaSM ~0.64 J/kg K and deltaTad ~0.3 K at m0H = 2 T) but ferromagnetism that gives rise to the enhanced MC effect of the central MC material. These properties could enable the MTECD to operate at high frequency.