Tuning the carrier concentration for thermoelectrical application in the quaternary Heusler compound Co_2TiAl_(1-x)Si_x

摘要

The family of half-metallic ferromagnets Co_2TiZ exhibits exceptional transport properties. The investigated compoundsCo_2TiAl_(1-x)Si_x (x = 0.25, 0.5, 0.75) show Curie temperatures (TC~s) that vary between 250 and 350 K, depending on the composition.Above TC the Seebeck coefficient remains constant. This makes them promising candidates for thermoelectric devices such asthermocouples with a tunable working range. The electrical resistivity data show an anomaly at TC which is attributed to changes inthe electronic structure and therefore in the carrier concentration.