Thursday, October 19, 2023 - 3:30pm


Superlattice structures are a powerful means of tailoring physical and chemical properties of materials. The modification of electronic structures at electrode–electrolyte interfaces is fundamental to efficient electrochemical energy conversion processes, and the intercalation of magnetic ions between van der Waals layers tunes the correlated electronic phenomena in these quantum materials, enabling the encoding of information for ultra-fast, ultralow-power, and non-volatile storage and retrieval. This talk will describe how azimuthal misalignment of atomically thin layers produces moiré superlattices that manifest a strong twist angle dependence of heterogeneous electrochemical kinetics in the case of twisted bilayer and twisted trilayer graphene electrodes with the greatest enhancement observed near the ‘magic angles’. These effects are driven by the angle-dependent engineering of moiré superlattice flat bands that dictate the electron transfer processes with the solution-phase redox couple. In addition, the talk will discuss how transition metal dichalcogenides intercalated with open-shell transition metals represent a family of materials allowing fine control over the chemical and electronic structure of a magnetic material to tailor the interplay between (anti)ferromagnetic exchange, magnetocrystalline anisotropy, and anisotropic exchange (Dzyaloshinskii–Moriya interactions) to bring about exotic magnetic orders in two-dimensional materials or bulk crystals. The role of intercalant disorder on magnetic order will be discussed in the case of chiral helimagnets and spin glass phases. The design and manipulation of superlattices structures is therefore shown to serve as an unparalleled platform for systematically interrogating and exploiting the dependence of physical and chemical phenomena on electronic structure.


Kwabena Bediako


University of California, Berkeley


RH 104