Oral: Study on Electronic Structure and Electron-phonon Coupling of Spinel Oxide Superconductor LiTi₂O₄

LiTi₂O₄ is known for its remarkably high critical transition temperature as a spinel superconductor. The spin-orbital fluctuations, the mixed valences, and d-d electron correlations [1-3] may be responsible for many novel behavior of the superconductivity in LiTi₂O_4. Recent angle-dependent magnetoresistance measurements have unveiled anisotropic magnetoresistance signals in LiTi₂O₄ thin films below the superconducting transition temperature (Tc). This observation suggests that LiTi₂O₄ may be a promising candidate for d-wave superconductors [4]. Despite numerous investigations, the superconductivity mechanism of LiTi₂O₄ has remained Controversial. In our latest study, we have employed in-situ measurements to obtain a comprehensive electronic structure and ultra-low-temperature tunneling spectrum of LiTi₂O₄. Our findings shed light on the electronic structure, electron-electron correlations, and energy gap structure of LiTi₂O₄. Furthermore, we have discovered a remarkably strong and anisotropic electron-phonon coupling in this material. These observations provide valuable insights into the superconductivity mechanism of LiTi₂O₄, suggesting that it exhibits characteristics of a BCS superconductor with an anisotropic electron-phonon coupling strength.



References

[1]Tunstall, D. P. , Phys. Rev. B 50, 16541–16549 (1994).

[2]Chen, C. L. , Supercond. Sci. Technol. 24, 115007 (2011).

[3]Jin, K. ., Nat. Commun. 6:7183 (2015).

[4]Huanyi Xue. , ACS Nano , 16, 11, 19464–19471(2022)