Pressure-induced orbital reordering in Na$_2$CuF$_4$
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_ | 1866910901518467072 |
|---|---|
| author | Hiley, Craig I. Crawford, Catriona A. Bull, Craig L. Funnell, Nicholas P. Dey, Urmimala Bristowe, Nicholas C. Walton, Richard I. Senn, Mark S. |
| author_facet | Hiley, Craig I. Crawford, Catriona A. Bull, Craig L. Funnell, Nicholas P. Dey, Urmimala Bristowe, Nicholas C. Walton, Richard I. Senn, Mark S. |
| contents | The high-pressure behaviour of Na$_2$CuF$_4$ is explored by powder neutron diffraction and density functional theory (DFT) calculations. A first-order phase transition is observed to take place between 2.4 - 2.9 GPa, involving a reorientation of the Jahn-Teller (JT) long axes of the (CuF6) octahedra (and therefore the d$_{z^2}$ Cu orbitals), in agreement with our DFT calculations which suggest a transition at 2.8 GPa. The transition can be described as being between a state of ferro-orbital order and one of A-type antiferro-orbital order, reflecting a shift in the associated electronic instability from being in the zone-center to zone boundary of the first Brillouin zone of the parent structure, with pressure. This change results in a decoupling of magnitude of the associated Jahn-Teller distortion of the Cu-F bond lengths from the lattice strain. This scenario is supported by our observations that the compressibility of the pre-transition phase is highly anisotropic, whilst in the post-transition phase it becomes almost isotropic, and that we observed no further decrease of the magnitude the JT distortion up to 5 GPa, or melting of the OO in our DFT calculations up to at least 5 GPa. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2504_01120 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Pressure-induced orbital reordering in Na$_2$CuF$_4$ Hiley, Craig I. Crawford, Catriona A. Bull, Craig L. Funnell, Nicholas P. Dey, Urmimala Bristowe, Nicholas C. Walton, Richard I. Senn, Mark S. Strongly Correlated Electrons Materials Science The high-pressure behaviour of Na$_2$CuF$_4$ is explored by powder neutron diffraction and density functional theory (DFT) calculations. A first-order phase transition is observed to take place between 2.4 - 2.9 GPa, involving a reorientation of the Jahn-Teller (JT) long axes of the (CuF6) octahedra (and therefore the d$_{z^2}$ Cu orbitals), in agreement with our DFT calculations which suggest a transition at 2.8 GPa. The transition can be described as being between a state of ferro-orbital order and one of A-type antiferro-orbital order, reflecting a shift in the associated electronic instability from being in the zone-center to zone boundary of the first Brillouin zone of the parent structure, with pressure. This change results in a decoupling of magnitude of the associated Jahn-Teller distortion of the Cu-F bond lengths from the lattice strain. This scenario is supported by our observations that the compressibility of the pre-transition phase is highly anisotropic, whilst in the post-transition phase it becomes almost isotropic, and that we observed no further decrease of the magnitude the JT distortion up to 5 GPa, or melting of the OO in our DFT calculations up to at least 5 GPa. |
| title | Pressure-induced orbital reordering in Na$_2$CuF$_4$ |
| topic | Strongly Correlated Electrons Materials Science |
| url | https://arxiv.org/abs/2504.01120 |