QMNO Lab@NotreDame
Ongoing Projects
We apply novel scanning probe techniques to study emergent phenomena in two-dimensional materials. Our research is based on utilizing coupling between light and matter at a scale of several orders of magnitudes below the diffraction limit gaining important insights into fundamental properties of strongly correlated condensed matter systems. Recently discovered, magic angle twisted bilayer graphene (MATBG) and other moiré materials featuring electronic flat bands opened a whole new pathway to explore strong electronic interactions with unprecedented tuneability where a sample can exhibit (unconventional) superconductivity, topology and correlated insulators simply by electrically tuning its charge carrier density. Now we want to understand what light can teach us about their fundamental properties. By controlled stacking of different two-dimensional materials we study:
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Emergent phenomena in graphene based van der Waals heterostructures
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Semiconductor-based moiré superlattices
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Polaritons and light-matter interaction in strongly correlated systems
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Local photovoltage generation and thermodynamics properties
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Spectroscopy of moiré materials at the nanoscale
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Unconventional superconductivity
2D Materials
Moiré quantum matter
In early 2018, group of Prof. Pablo Jarillo-Herrero (MIT) managed to fabricate magic-angle twisted bilayer graphene devices (MATBG) with the angle misalignment between the adjacent graphene layers of only 1.1 degree. This very special angle allows the two graphenes’ Dirac bands to hybridize in a very peculiar way creating a pair of flat electronic bands in the zero-energy limit, which host superconducting, ferromagnetic and correlated insulating states. Its striking resemblances with other high-temperature superconductors generated an intense wave of theoretical and experimental research and opened a new field named “twistronics”. Read more:
Scanning near-field optical microscopy (s-SNOM)
Our current interest is to explore electronic interactions in moiré materials with a strongly confined light by using cryogenic near-field optical microscopy. Our preliminary results reveal interband plasmonic modes in twisted bilayer graphene devices. Many other interesting polaritonic modes are predicted in a number of moiré materials, which will remain the main focus of our research efforts. Read more:
Quantum transport in 2D
heterostructures
Tuneability of two-dimensional materials makes them an attractive candidate to study strongly correlated physics and attempt to learn something new about other strongly correlated systems. In one of our previous works we study the effect of electronic interactions screening in MATBG by proximitizing it to a closely located graphite back gate only a few nanometers away from the graphene plane. Turns out that in this case correlated insulators disappear from the phase space meaning that the superconductors in MATBG are not necessarily tied to them, unlike the case of high-temperature cuprate superconductors.
Read more: