Large phonon drag thermopower boosted by massive electrons and phonon leaking in LaAlO<sub>3</sub>/LaNiO<sub>3</sub>/LaAlO<sub>3</sub> heterostructure.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 34709840.
- Also identified by DOI 10.1021/acs.nanolett.1c03143 and PMC identifier 8587880.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
An unusually large thermopower (<i>S</i>) enhancement is induced by heterostructuring thin films of the strongly correlated electron oxide LaNiO<sub>3</sub>. The phonon-drag effect, which is not observed in bulk LaNiO<sub>3</sub>, enhances <i>S</i> for thin films compressively strained by LaAlO<sub>3</sub> substrates. By a reduction in the layer thickness down to three unit cells and subsequent LaAlO<sub>3</sub> surface termination, a 10 times <i>S</i> enhancement over the bulk value is observed due to large phonon drag <i>S</i> (<i>S</i><sub>g</sub>), and the <i>S</i><sub>g</sub> contribution to the total <i>S</i> occurs over a much wider temperature range up to 220 K. The <i>S</i><sub>g</sub> enhancement originates from the coupling of lattice vibration to the d electrons with large effective mass in the compressively strained ultrathin LaNiO<sub>3</sub>, and the electron-phonon interaction is largely enhanced by the phonon leakage from the LaAlO<sub>3</sub> substrate and the capping layer. The transition-metal oxide heterostructures emerge as a new playground to manipulate electronic and phononic properties in the quest for high-performance thermoelectrics.