Isaac Craig is currently a 5th year Ph.D. candidate in the Department of Chemistry where he is advised by Professor D. Kwabena Bediako. Isaac received a B.S. in Chemistry from the University of California, Berkeley, where he began research modeling atmospheric nitrogen transport under Professor Ronald Cohen and later worked on improving trial wavefunction and optimization choices for modeling correlated molecular systems with quantum Monte Carlo under Professor Eric Neuscamman. He began research within the lab of Sinéad M. Griffin at Lawrence Berkeley National Laboratory before returning to Berkeley, where he used density functional theory and lattice Monte Carlo to model transition metal intercalant ordering in transition metal dichalcogenides.
Isaac’s doctoral research focuses on developing methods to extract the atomic structure of buried layers from interference fringes in transmission electron microscopy data of moiré systems and leveraging these techniques to understand the implications of intrinsic and applied strain on systems with emergent properties of interest, such as twisted MoS2 bilayers, WSe2/MoS2 bilayers, and graphene trilayers.
As a Kavli ENSI fellow, Isaac will expand the aforementioned Bragg Interferometry (BI) approach to resolve the mechanism of moiré relaxation in quasi-crystalline regimes of twisted graphene trilayers (TGTs). While TGTs are one route to obtaining tunable quasi-crystalline order on a measurable scale, they relax out of this aperiodicity for many twist angle choices. The precise breakdown of these deformations across interlayer angle choices and the role of hBN encapsulation remain unknown. He aims to increase the resolution of this BI methodology to enable a more precise breakdown of rotational and dilational deformation by extending the approach to be compatible with smaller probe sizes and finite strain theory. He will also investigate the polariton properties of moiré superlattices formed between hexagonal boron nitride (hBN) and graphene by correlating structural measurements with scanning transmission electron microscopy electron energy loss spectroscopy (STEM-EELS) acquired as part of an ongoing collaboration with Oak Ridge National Laboratory.