Metallic crossover through the tilt-free transition in La$_3$Ni$_2$O$_7$ at high pressure and temperature
Fuente:
arXiv
Saved in:
| Main Authors: | , , , , , , , , , , |
|---|---|
| Format: | Preprint |
| Published: |
2026
|
| Subjects: | |
| Online Access: | |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| _version_ | 1866911712781795328 |
|---|---|
| author | Michon, Bastien Yu, Yingpeng D'Alò, Beatrice Stellino, Elena Németh, Gergely Wang, Bosen Sun, Jianping Cheng, Jinguang Postorino, Paolo Borondics, Ferenc Capitani, Francesco |
| author_facet | Michon, Bastien Yu, Yingpeng D'Alò, Beatrice Stellino, Elena Németh, Gergely Wang, Bosen Sun, Jianping Cheng, Jinguang Postorino, Paolo Borondics, Ferenc Capitani, Francesco |
| contents | La$_3$Ni$_2$O$_7$, a bilayer nickelate with Ruddlesden-Popper structure, undergoes a pressure-induced structural transition from a tilted Amam phase to an untilted Fmmm (or I4/mmm) phase near 10-15 GPa, concomitant with the emergence of high-T$_c$ superconductivity ($T_c \sim 80$ K). Despite intense interest, the phase boundaries and the impact of structural changes on the electronic properties remain unclear. Here, we combine high-pressure and high-temperature Raman and synchrotron-based infrared spectroscopies to map the structural and electronic evolutions. Raman measurements confirm the pressure-driven structural transition and reveal the emergence of Fano line shapes, indicating enhanced electron-phonon coupling. High-temperature data show analogous spectral signatures above 544 K, suggesting an unreported upper temperature limit of the \textit{Amam} phase within the T-P phase diagram of this system. Infrared reflectivity measurements evidence a concomitant enhanced metallicity, with a tremendous two-order-of-magnitude increase in carrier density, marking a crossover from a weakly to highly metallic state. These results establish a unified picture of the structural transition and its strong coupling to the electronic properties. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2605_01651 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Metallic crossover through the tilt-free transition in La$_3$Ni$_2$O$_7$ at high pressure and temperature Michon, Bastien Yu, Yingpeng D'Alò, Beatrice Stellino, Elena Németh, Gergely Wang, Bosen Sun, Jianping Cheng, Jinguang Postorino, Paolo Borondics, Ferenc Capitani, Francesco Superconductivity La$_3$Ni$_2$O$_7$, a bilayer nickelate with Ruddlesden-Popper structure, undergoes a pressure-induced structural transition from a tilted Amam phase to an untilted Fmmm (or I4/mmm) phase near 10-15 GPa, concomitant with the emergence of high-T$_c$ superconductivity ($T_c \sim 80$ K). Despite intense interest, the phase boundaries and the impact of structural changes on the electronic properties remain unclear. Here, we combine high-pressure and high-temperature Raman and synchrotron-based infrared spectroscopies to map the structural and electronic evolutions. Raman measurements confirm the pressure-driven structural transition and reveal the emergence of Fano line shapes, indicating enhanced electron-phonon coupling. High-temperature data show analogous spectral signatures above 544 K, suggesting an unreported upper temperature limit of the \textit{Amam} phase within the T-P phase diagram of this system. Infrared reflectivity measurements evidence a concomitant enhanced metallicity, with a tremendous two-order-of-magnitude increase in carrier density, marking a crossover from a weakly to highly metallic state. These results establish a unified picture of the structural transition and its strong coupling to the electronic properties. |
| title | Metallic crossover through the tilt-free transition in La$_3$Ni$_2$O$_7$ at high pressure and temperature |
| topic | Superconductivity |
| url | https://arxiv.org/abs/2605.01651 |