Ionic liquid gating induced two superconductor-insulator phase transitions in spinel oxide Li$_{1 \pm x}$Ti$_2$O$_{4-\delta}$
| Autor: | Wei, Zhongxu, Li, Qian, Gong, Ben-Chao, Wei, Xinjian, Hu, Wei, Ni, Zhuang, He, Ge, Qin, Mingyang, Kusmartseva, Anna, Kusmartsev, Fedor V., Yuan, Jie, Zhu, Beiyi, Chen, Qihong, Chen, Jian-Hao, Liu, Kai, Jin, Kui |
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| Rok vydání: | 2021 |
| Předmět: | |
| Zdroj: | Phys. Rev. B 103, 140501 (2021) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1103/PhysRevB.103.L140501 |
| Popis: | The associations between emergent physical phenomena (e.g., superconductivity) and orbital, charge, and spin degrees of freedom of $3d$ electrons are intriguing in transition metal compounds. Here, we successfully manipulate the superconductivity of spinel oxide Li$_{1\pm x}$Ti$_2$O$_{4-\delta}$ (LTO) by ionic liquid gating. A dome-shaped superconducting phase diagram is established, where two insulating phases are disclosed both in heavily electron-doping and hole-doping regions. The superconductor-insulator transition (SIT) in the hole-doping region can be attributed to the loss of Ti valence electrons. In the electron-doping region, LTO exhibits an unexpected SIT instead of a metallic behavior despite an increase in carrier density. Furthermore, a thermal hysteresis is observed in the normal state resistance curve, suggesting a first-order phase transition. We speculate that the SIT and the thermal hysteresis stem from the enhanced $3d$ electron correlations and the formation of orbital ordering by comparing the transport and structural results of LTO with the other spinel oxide superconductor MgTi$_2$O$_4$, as well as analysing the electronic structure by first-principles calculations. Further comprehension of the detailed interplay between superconductivity and orbital ordering would contribute to the revealing of unconventional superconducting pairing mechanism. Comment: 6 pages, 4 figures |
| Databáze: | arXiv |
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