Anisotropic electron-phonon coupling in the spinel oxide superconductor

Anisotropic electron-phonon coupling has been widely observed in various quasi-two dimensional superconductors like perovskite copper oxides, 2H-NbSe2 and MgB2, which exhibit unexpected critical superconducting transition temperature (Tc). Hitherto, LiTi2O4 with a remarkable Tc up to 13 K is the only known oxide superconductor in spinels, the origin of which remains obscured mainly due to the lack of high-quality single crystals. By probing tunneling spectra of single crystalline thin films in different orientations, an intrinsic anisotropic electron-phonon coupling is firstly observed in such a cubic system as well, thereby giving insight to the issue of key ingredients in understanding the novel superconducting systems.