Abstract
We present a combined experimental and theoretical study of the charge transport properties of epitaxial thin films. We found that the Hall coefficient of strongly depends on hydrogen content and unit-cell volume: Nearly stoichiometric films with large unit-cell volumes showed positive Hall coefficients at 4 K, whereas samples with and small unit-cell volumes showed negative Hall coefficients at 4 K. Our density functional theory calculations reveal that the volume change leads to the change in the aspect ratio of the tetragonal lattice, thereby lifting the degeneracy of Ti states, and alters the contributions of electrons and holes at the Fermi surface and the sign of the Hall coefficient. The present study clarifies the important role of the lattice symmetry in determining the charge carrier polarity, and we suggest that electronic properties of metal hydrides can be tuned by the lattice parameters via the hydrogen contents.
3 More- Received 3 September 2019
- Accepted 7 August 2020
DOI:https://doi.org/10.1103/PhysRevResearch.2.033467
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.
Published by the American Physical Society