Raja Labs
Nanoscale Spectroscopy
Molecular Foundry · Lawrence Berkeley National Laboratory
Light, electrons & atomically thin matter
We image and time-resolve excitons, phonons, and charge at the interfaces of two-dimensional heterostructures, down to the sub-nanometer and femtosecond scales.
Our work combines ultrafast optical spectroscopy, electron energy-loss and cathodoluminescence microscopy, and ultrafast electron diffraction to reveal how dielectric environment, moiré potentials, and non-equilibrium phonons shape the physics of van der Waals materials.
Painting potential landscapes on an atomically thin canvas.
News
All news →Ambipolar metal-insulator transition in bilayer MoSe₂ posted to arXiv with the Wang and Ma groups.
Archana gives invited talks at Flatlands Beyond Graphene (Dresden) and the Bay Area Light Sources MeV-UED workshop.
Sub-nanoscale visualization of reconstruction-driven moiré exciton localization posted to arXiv.
Ferroelectricity in atomic-scale TiO₂ dielectric films published in Science with the Salahuddin group.
Keynote at the SDSU Computational Science Research Center workshop on bridging experiment, theory, and AI.
Key Publications
All publications →† corresponding · * equal contribution · > 4600 citations, h-index 27
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1.
S. Susarla*, M. H. Naik*, D. D. Blach, J. Zipfel, T. Taniguchi, K. Watanabe, L. Huang, R. Ramesh, F. H. da Jornada, S. G. Louie†, P. Ercius†, A. Raja†. “Hyperspectral imaging of excitons within a moiré unit-cell with a sub-nanometer electron probe.” Science 378, 1235 (2022)
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2.
A. Sood†, J. Haber, J. D. Carlström, et al., A. Lindenberg†, F. H. da Jornada†, A. Raja†. “Bidirectional phonon emission in two-dimensional heterostructures triggered by ultrafast charge transfer.” Nature Nanotechnology 18, 29 (2023)
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3.
A. Raja*†, L. Waldecker*, J. Zipfel, Y. Cho, S. Brem, et al., T. F. Heinz, A. Chernikov†. “Dielectric disorder in two-dimensional materials.” Nature Nanotechnology 14, 832 (2019)
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4.
A. Raja†, A. Chaves, J. Yu, G. Arefe, H. M. Hill, et al., D. R. Reichman, A. Chernikov†. “Coulomb engineering of the bandgap and excitons in two-dimensional materials.” Nature Communications 8, 15251 (2017)