Response characteristics of (La,Ca)Mn1+δO3 films for heat fluxes based on the transverse thermoelectric effect

Abstract

Inclined epitaxial (La,Ca)Mn1+δO3 films (-0.3 ≤ δ ≤ 0.1) have been prepared on the miscut 12° STO single crystal substrates. The conductivity gradually increases from 1.51 × 103 S/m for (La,Ca)Mn0.7O3 to 1.23 × 104 S/m for (La, Ca)MnO3, and then slightly decreases to 1.12 × 104 S/m for (La, Ca)Mn1.1O3 films. The enhanced conductivity results in the increase of electron thermal conductivity, so the sensitivity gradually decreases from 12.44 μV/(kW/m2) for (La,Ca)Mn0.7O3 to 7.69 μV/(kW/m2) for (La,Ca)MnO3. As the Mn content continues to increase, even if the conductivity of (La,Ca)Mn1.1O3 decreases, the sensitivity still decreases to 6.12 μV/(kW/m2) due to the deteriorated Seebeck coefficient anisotropy. Additionally, the response time decreases to 22 ns for (La,Ca)MnO3 with increased conductivity, and then slightly increases to 24 ns for (La,Ca)Mn1.1O3 due to the decrease in conductivity. The above results indicate that the sensitivity and response time show a similar trend with the conductivity, which could serve as a reference to fabricate heat flux sensors based on the TTE effect by designing materials.