Breaking of Thermopower-Conductivity Trade-Off in LaTiO₃ Film around Mott Insulator to Metal Transition.

ABSTRACT: Introducing artificial strain in epitaxial thin films is an effective strategy to alter electronic structures of transition metal oxides (TMOs) and to induce novel phenomena and functionalities not realized in bulk crystals. This study reports a breaking of the conventional trade-off relation in thermopower (S)-conductivity (σ) and demonstrates a 2 orders of magnitude enhancement of power factor (PF) in compressively strained LaTiO₃ (LTO) films. By varying substrates and reducing film thickness down to 4 nm, the out-of-plane to the in-plane lattice parameter ratio is controlled from 0.992 (tensile strain) to 1.034 (compressive strain). This tuning induces the electronic structure change from a Mott insulator to a metal and leads to a 10³ -fold increase in σ up to 2920

SUBMITTER: Katase T 

PROVIDER: S-EPMC8655177 | biostudies-literature | 2021 Dec

REPOSITORIES: biostudies-literature