Steef Smit

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Unconventional superconductivity and its interplay with various ordered phases has long been a central topic in condensed matter research. Multilayered cuprates and nickelates in particular have garnered lots of attention as these cuprates hold the record for highest critical temperature at ambient pressure, where the nickelates have only very recently been discovered to host superconductivity at high pressures or strain. I will discuss two recent papers [1][2] showing photoemission signatures of a layer-selective charge density wave in the trilayer cuprate Bi2223[1], and of an incommensurate spin density wave in the multilayered nickelate La2Ni3O7[2]. We propose a novel mechanism where interfacing superconducting layers of distinct doping optimizes both pairing and phase coherence in the combined structure, thereby maximizing TC. In the nickelates, we additionally use ARPES dichroism to show that the first electron removal states have a symmetry reminiscent of the Zhang-Rice-singlets and three-spin-polarons found in the cuprates, suggesting a deep connection between the low energy electronic structures of the two material families.

[1] S. Smit*, M. Bluschke* et al, Coherence and pairing enhancement in a trilayer cuprate with layer-selective charge order (2025) arXiv:2506.01448

[2] CC. Au-Yeung*, X. Chen*, S.Smit*, M. Bluschke* et al, Universal electronic structure of multi-layered nickelates via oxygen-centered planar orbitals, Nature Physics (2026) arXiv:2502.20450

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The University of British Columbia
PH2
Contact: Erwann Bocquillon / Matteo Cacco