| Autor: |
Ye, Yuhao, Wang, Jinhua, Nie, Pan, Zuo, Huakun, Li, Xiaokang, Behnia, Kamran, Zhu, Zengwei, Fauqué, Benoît |
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| Zdroj: |
Nature Communications; 11/12/2024, Vol. 15 Issue 1, p1-7, 7p |
| Abstrakt: |
In graphite, a moderate magnetic field confines electrons and holes into their lowest Landau levels. In the extreme quantum limit, two insulating states with a dome-like field dependence of the their critical temperatures are induced by the magnetic field. Here, we study the evolution of the first dome (below 60 T) under hydrostatic pressure up to 1.7 GPa. With increasing pressure, the field-temperature phase boundary shifts towards higher magnetic fields, yet the maximum critical temperature remains unchanged. According to our fermiology data, pressure amplifies the density and the in-plane effective cyclotron mass of hole-like and electron-like carriers. Thanks to this information, we verify the persistent relevance of the BCS relation between the critical temperature and the density of states in the weak-coupling boundary of the dome. In contrast, the strong-coupling summit of the dome does not show any detectable change with pressure. We argue that this is because the out-of-plane BCS coherence length approaches the interplane distance that shows little change with pressure. Thus, the BCS-BEC crossover is tunable by magnetic field and pressure, but with a locked summit. A large magnetic field induces a metal-insulator transition in graphite, which manifests as a dome in the phase diagram. Ye et al. show that this dome is an example of an electron-hole pair BCS-BEC crossover, tuneable by hydrostatic pressure with a locked summit temperature. [ABSTRACT FROM AUTHOR] |
| Databáze: |
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