X. X. Wu

Enhanced superconductivity accompanying a Lifshitz transition in electron-doped FeSe monolayer

The origin of enhanced superconductivity over 50 K in the recently discovered FeSe monolayer films grown on SrTiO3 (STO), as compared to 8 K in bulk FeSe, is intensely debated. As with the ferrochalcogenides AxFe2−ySe2 and potassium-doped FeSe, which also have a relatively high-superconducting critical temperature (Tc), the Fermi surface (FS) of the FeSe/STO monolayer films is free of hole-like FS, suggesting that a Lifshitz transition by which these hole FSs vanish may help increasing Tc. However, the fundamental reasons explaining this increase of Tc remain unclear. Here we report a 15 K jump of Tc accompanying a second Lifshitz transition characterized by the emergence of an electron pocket at the Brillouin zone centre, which is triggered by high-electron doping following in situ deposition of potassium on FeSe/STO monolayer films. Our results suggest that the pairing interactions are orbital dependent in generating enhanced superconductivity in FeSe.

Observation of two distinct d x z / d y z band splittings in FeSe

We report the temperature evolution of the detailed electronic band structure in FeSe single-crystals measured by angle-resolved photoemission spectroscopy (ARPES), including the degeneracy removal of the

Correlation between superconductivity and bond angle of CrAs chain in non-centrosymmetric compounds A2Cr3As3 (A = K, Rb).

d_{xz}

Disentangling the surface and bulk electronic structures of LaOFeAs

and

Observation of two distinct

d_{yz}

d_{xz}/d_{yz}

orbitals at the

band splittings in FeSe

\Gamma

Observation of two distinctdxz/dyzband splittings in FeSe

/Z and M points, and the orbital-selective hybridization between the

Observation of a Van Hove singularity and implication for strong-coupling induced Cooper pairing in KFe2As2

d_{xy}

Cooper Pairing and Phase Coherence in Iron Superconductor Fe1+x(Te,Se)

and