Anomalous Nernst effect in ferromagnetic Mn$_5$Ge$_3$C$_x$ thin films on insulating sapphire

TL;DR

This study explores the anomalous Nernst effect in Mn$_5$Ge$_3$C$_x$ thin films, revealing a significant enhancement with carbon doping, which is promising for spintronic thermoelectric applications.

Contribution

It provides experimental analysis of the anomalous Nernst effect in Mn$_5$Ge$_3$C$_x$ films and shows how carbon content influences thermoelectric properties.

Findings

ANE increases with carbon content up to x=0.8

ANE is enhanced threefold compared to Mn$_5$Ge$_3$

Deviations observed between calculated and measured ANE at x=0.8

Abstract

Investigating the thermoelectric properties of ferromagnets is important for the development of future microelectronic devices for efficient energy conversion purposes. Ferromagnetic Mn$_5$Ge$_3$C$_x$ thin films with a Curie temperature up to $T_{\rm C}$ = 450 K well above room temperature are potential candidates for spintronic applications by integration into CMOS heterostructures. In this work, the thermoelectric power, in particular, the anomalous Nernst effect (ANE) has been investigated experimentally for magnetron sputtered thin films on sapphire (11-20) substrates. The ANE gradually increases with increasing carbon content x up to a maximum value obtained for x=0.8 in line with earlier investigations of the magnetization and anomalous Hall effect. The ANE is strongly enhanced by a factor three compared to the parent Mn$_5$Ge$_3$ compound. However, for x=0.8 we observe a clear deviation of the calculated ANE from the measured values.