Uncovering the spin-valley order of correlated phases in magic-angle graphene - Livestream

The twist angle between adjacent two-dimensional layers provides a powerful tuning knob to tailor electronic properties. One archetypal example is magic-angle twisted bilayer graphene (MATBG), whose flat low-energy bands host a variety of broken-symmetry ground states. However, despite intensive effort, the spin and valley order of these phases and their low-energy excitations remain poorly understood. In this talk, I will describe local electronic compressibility measurements that enable us to map out the flavor phase diagram and correlated Hofstadter spectrum in MATBG. We identify intervalley-coherent insulators and spin skyrmion excitations at low magnetic fields and deduce the spin polarization of Chern insulators at high field. I will discuss the implications of these findings and how microscopic parameters affect the delicate competition between distinct correlated ground states.

Speaker: Ben Feldman, Stanford University

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