Regensburg 2025 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 43: Twisted Materials / Systems (joint session TT/HL)
HL 43.1: Talk
Wednesday, March 19, 2025, 17:00–17:15, H31
Formation, persistence and ordering of local moments in magic angle twisted bilayer graphene — •Lorenzo Crippa1,2, Gautam Rai1, Dumitru Călugăru3,13, Haoyu Hu4, Luca de' Medici5, Antoine Georges6,7,8,9, Bogdan Andrei Bernevig3,4,10, Roser Valentí11, Giorgio Sangiovanni2, and Tim Wehling1,12 — 1University of Hamburg — 2University of Würzburg — 3Princeton University — 4DIPC, Donostia-San Sebastian — 5ESPCI, Paris — 6Collège de France, Paris — 7Flatiron Institute, New York — 8École Polytechnique, Palaiseau Cedex — 9Université de Genève — 10IKERBASQUE, Bilbao — 11Goethe University Frankfurt — 12Hamburg CUI — 13University of Oxford
The physics of magic angle twisted bilayer graphene (MATBLG) is remarkably diverse across a wide range of dopings and temperatures.
By means of a Dynamical Mean-Field Theory (DMFT) approach, we study the effect of electronic correlations in MATBLG, with particular focus on the physics of local spin and valley isospin moments. We analyze their magnitude and screening across a broad temperature range, discuss the limits of very low and infinite temperature, and obtain two different scales for their formation (around 100 K) and ordering (around 10 K).
We discuss their implications in terms of transport properties of the system (e.g. resistivity) and of spectral features (resonance peaks) and contextualize our findings with recent experimental results.
Keywords: Twisted Bilayer Graphene; Local Moments; Pomeranchuk Effect; Kondo effect