Electronic instabilities in Penrose quasicrystals: Competition, coexistence, and collaboration of order

Quasicrystals lack translational symmetry, but can still exhibit long-range order, promoting them to candidates for unconventional physics beyond the paradigm of crystals. Here, we apply a real-space functional renormalization group approach to the prototypical quasicrystalline Penrose tiling Hubbard model treating competing electronic instabilities in an unbiased, beyond-mean-field fashion. Our work reveals a delicate interplay between charge and spin degrees of freedom in quasicrystals. Depending on the range of interactions and hopping amplitudes, we unveil a rich phase diagram including antiferromagnetic orderings, charge density waves, and subleading, superconducting pairing tendencies. For certain parameter regimes, we find a competition of phases, which is also common in crystals, but additionally encounter phases coexisting in a spatially separated fashion and ordering tendencies which mutually collaborate to enhance their strength. We therefore establish that quasicrystalline structures open up a route towards this rich ordering behavior uncommon to crystals and that an unbiased, beyond-mean-field approach is essential to describe this physics of quasicrystals correctly.

Automated summary

Quasicrystals exhibit unique physics with complex interplay between charge and spin degrees of freedom, leading to a rich phase diagram including antiferromagnetic orderings, charge density waves, and superconducting pairing tendencies. Competition of phases and enhanced ordering tendencies highlight the unconventional behavior of quasicrystals, requiring an unbiased approach to accurately describe their physics.