Visualizing the electronics of WS2/WSe2 superlattices with ARPES - Livestream

Superlattices of TMDCs and graphene have received well deserved attention by breaking the paradigm of “tunable” heterostructure electronics: moiré superlattices are functionally completely new materials hosting exotic correlations and bearing little surface resemblance to their parents. By using nanoARPES to measure the holistic band structures of WS2/WSe2, we examine the relationship between moiré phases and their constituent monolayers more closely. I will discuss the emergence of flat bands and strong interlayer hybridization as hallmarks of moiré TMDC materials and show that ARPES provides insight into the electronics of moiré materials despite inaccessibly small superlattice unit cells.

The second half of the talk pulls on a parallel thread by taking a broader perspective on how we interpret ARPES data. NanoARPES, which enabled our WS2/WSe2 measurements, offers an emerging strength for the technique by making it possible to “image” a material or device's electronics, but it requires complex and expensive instrumentation. In this section, I present one simple approach based on regularized signal unmixing which permits recovery of the ARPES spectra on materials with much larger beams.

Speaker: Conrad Stansbury, UC Berkeley

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