Doping asymmetry and layer-selective metal-insulator transition in trilayer K${}_{3+x}$C${}_{60}$

Abstract

Thin films provide a versatile platform to tune electron correlations and explore new physics in strongly correlated materials. Epitaxially grown thin films of the alkali-doped fulleride K${}_{3+x}$C${}_{60}$, for example, exhibit %various intriguing phenomena, including Mott transitions and superconductivity, depending on dimensionality and doping. Surprisingly, in the trilayer case, a strong electron-hole doping asymmetry has been observed in the superconducting phase, which is absent in the three-dimensional bulk limit. Using density-functional theory plus dynamical mean-field theory, we show that this doping asymmetry results from a substantial charge reshuffling from the top layer to the middle layer. While the nominal filling per fullerene is close to $n=3$, the top layer rapidly switches to an $n=2$ insulating state upon hole doping, which \textcolor{black}{implies a} doping asymmetry of the superconducting gap. The interlayer charge transfer and layer-selective metal-insulator transition result from the interplay between crystal field splittings, strong Coulomb interactions, and an effectively negative Hund coupling. This peculiar charge reshuffling is absent in the monolayer system, which is an $n=3$ Mott insulator, as expected from the nominal filling.

5+3 pages, 4+3 figures

References in corpus (13)

• Continuous-time Monte Carlo methods for quantum impurity models
• High-spin to low-spin and orbital polarization transitions in multiorbital Mott systems
• Dynamical mean-field theory using Wannier functions: a flexible route to electronic structure calculations of strongly correlated materials
• Modeling the Unconventional Superconducting Properties of Expanded A${}_3$C${}_{60}$ Fullerides
• Monolayer FeSe on SrTiO${}_3$
• Effective Onsite Interaction for Dynamical Mean-Field Theory
• $i$QIST: An open source continuous-time quantum Monte Carlo impurity solver toolkit
• A spin-freezing perspective on cuprates
• $i$QIST v0.7: An open source continuous-time quantum Monte Carlo impurity solver toolkit
• Unconventional Pairing from Local Orbital Fluctuations in Strongly Correlated A${}_3$C${}_{60}$
• Investigation of the effective interactions for the Emery model by the constrained random-phase approximation and constrained functional renormalization group
• Entropy and electronic orders of the three-orbital Hubbard model with antiferromagnetic Hund coupling
• Spectral changes in layered $f$-electron systems induced by Kondo hole substitution in the boundary-layer

Cited by in corpus (3)

• Fractionalization on the Surface: Is Type-II Terminated $1T$-TaS${}_2$ Surface an Anomalously Realized Spin Liquid?
• Quantum many-body solver using artificial neural networks and its applications to strongly correlated electron systems
• Instability of Pa$\overline{3}$ Cs${}_3$C${}_{60}$ at ambient pressure and superconducting state of the FCC phase