Pressure-tunable structural instabilities in single-layer-trilayer La$_3$Ni$_2$O$_7$
Fuente:
arXiv
Guardado en:
| Autor principal: | |
|---|---|
| Formato: | Preprint |
| Publicado: |
2024
|
| Materias: | |
| Acceso en línea: | |
| Etiquetas: |
Agregar Etiqueta
Sin Etiquetas, Sea el primero en etiquetar este registro!
|
| _version_ | 1866915085549568000 |
|---|---|
| author | Subedi, Alaska |
| author_facet | Subedi, Alaska |
| contents | Layered nickelates are believed to exhibit superconductivity similar
to that found in the cuprates. However, the precise crystal
structure of the superconducting phase of the layered nickelates has
not been fully clarified. Here, I use first principles calculations
to study the pressure dependence of the structural instabilities in
the single-layer-trilayer La$_3$Ni$_2$O$_7$, which is one member of
the layered nickelates family that also shows signatures of
superconductivity. I find a nearly dispersionless nondegenerate
phonon branch in the parent $P4/mmm$ phase that is unstable along
the Brillouin zone edge $M$ $(\frac{1}{2}, \frac{1}{2}, 0)$
$\rightarrow$ $A$ $(\frac{1}{2},\frac{1}{2},\frac{1}{2})$ at all
investigated pressures up to 30 GPa. Calculations show additional
doubly-degenerate instabilities along the edge $MA$ at lower
pressures. I used group-theoretical analysis to identify the
distinct low-symmetry distortions possible due to these
instabilities and generated them using the eigenvectors of the
unstable modes. Structural relaxations show that the lowest energy
structures at 0 and 10 GPa involve condensation of both the
nondegenerate and doubly-degenerate instabilities, which is in
contrast to the experimental refinements that involve condensation
of only the doubly-degenerate branch. I also find that
structural distortions are energetically favorable at 20 GPa,
contrary to the experiments that do not observe any distortions of
the parent $P4/mmm$ structure at high pressures. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2412_21150 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Pressure-tunable structural instabilities in single-layer-trilayer La$_3$Ni$_2$O$_7$ Subedi, Alaska Superconductivity Materials Science Strongly Correlated Electrons Layered nickelates are believed to exhibit superconductivity similar to that found in the cuprates. However, the precise crystal structure of the superconducting phase of the layered nickelates has not been fully clarified. Here, I use first principles calculations to study the pressure dependence of the structural instabilities in the single-layer-trilayer La$_3$Ni$_2$O$_7$, which is one member of the layered nickelates family that also shows signatures of superconductivity. I find a nearly dispersionless nondegenerate phonon branch in the parent $P4/mmm$ phase that is unstable along the Brillouin zone edge $M$ $(\frac{1}{2}, \frac{1}{2}, 0)$ $\rightarrow$ $A$ $(\frac{1}{2},\frac{1}{2},\frac{1}{2})$ at all investigated pressures up to 30 GPa. Calculations show additional doubly-degenerate instabilities along the edge $MA$ at lower pressures. I used group-theoretical analysis to identify the distinct low-symmetry distortions possible due to these instabilities and generated them using the eigenvectors of the unstable modes. Structural relaxations show that the lowest energy structures at 0 and 10 GPa involve condensation of both the nondegenerate and doubly-degenerate instabilities, which is in contrast to the experimental refinements that involve condensation of only the doubly-degenerate branch. I also find that structural distortions are energetically favorable at 20 GPa, contrary to the experiments that do not observe any distortions of the parent $P4/mmm$ structure at high pressures. |
| title | Pressure-tunable structural instabilities in single-layer-trilayer La$_3$Ni$_2$O$_7$ |
| topic | Superconductivity Materials Science Strongly Correlated Electrons |
| url | https://arxiv.org/abs/2412.21150 |