Large phonon-drag thermopower polarity reversal in Ba-doped KTaO3
Fuente:
arXiv
Saved in:
| Main Authors: | , , , , , , , , |
|---|---|
| Format: | Preprint |
| Published: |
2025
|
| Subjects: | |
| Online Access: | |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1866913969494556672 |
|---|---|
| author | Nawwar, Mohamed Poage, Samuel Schwaigert, Tobias Gastiasoro, Maria N. Salmani-Rezaie, Salva Schlom, Darrell G. Ahadi, Kaveh Wooten, Brandi L. Heremans, Joseph P. |
| author_facet | Nawwar, Mohamed Poage, Samuel Schwaigert, Tobias Gastiasoro, Maria N. Salmani-Rezaie, Salva Schlom, Darrell G. Ahadi, Kaveh Wooten, Brandi L. Heremans, Joseph P. |
| contents | This study reports the observation of phonon-drag thermopower polarity reversal in Ba-doped KTaO3 thin films, mediated by electron-phonon Umklapp scattering. Epitaxial films with distinct carrier concentrations (3.7 x 10^20 cm^-3 and 4.9 x 10^19 cm^-3) were grown via molecular-beam epitaxy. In heavily doped samples, where the Fermi surface spans 80% of the Brillouin zone, the Umklapp condition is satisfied, reversing electron momentum. This manifests as a sign-reversal in the thermopower around 80 K upon cooling despite the sample having only n-type carriers. On the other hand, the lightly doped sample (4.9 x 10^19 cm^-3) exhibits only a negative thermopower down to 2 K. These results advance the understanding of Umklapp electron-phonon drag in oxides and highlight KTaO3's potential for engineering unconventional thermoelectric materials. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2508_00313 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Large phonon-drag thermopower polarity reversal in Ba-doped KTaO3 Nawwar, Mohamed Poage, Samuel Schwaigert, Tobias Gastiasoro, Maria N. Salmani-Rezaie, Salva Schlom, Darrell G. Ahadi, Kaveh Wooten, Brandi L. Heremans, Joseph P. Materials Science Superconductivity This study reports the observation of phonon-drag thermopower polarity reversal in Ba-doped KTaO3 thin films, mediated by electron-phonon Umklapp scattering. Epitaxial films with distinct carrier concentrations (3.7 x 10^20 cm^-3 and 4.9 x 10^19 cm^-3) were grown via molecular-beam epitaxy. In heavily doped samples, where the Fermi surface spans 80% of the Brillouin zone, the Umklapp condition is satisfied, reversing electron momentum. This manifests as a sign-reversal in the thermopower around 80 K upon cooling despite the sample having only n-type carriers. On the other hand, the lightly doped sample (4.9 x 10^19 cm^-3) exhibits only a negative thermopower down to 2 K. These results advance the understanding of Umklapp electron-phonon drag in oxides and highlight KTaO3's potential for engineering unconventional thermoelectric materials. |
| title | Large phonon-drag thermopower polarity reversal in Ba-doped KTaO3 |
| topic | Materials Science Superconductivity |
| url | https://arxiv.org/abs/2508.00313 |