Thermodynamic study of correlated electrons in moiré materials

Principal investigator

Dmitri K. Efetov, LMU Munich [webpage]

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Abstract

The mechanism of formation of highly ordered states, such as superconductors or magnets, from an incoherent ’strange-metal’ phase near a quantum critical point is a major conundrum reported in a variety of correlated materials, but remains to this day one of the biggest open questions in modern condensed matter physics. The recent prediction of flat bands and demonstration of strong electronic correlations, superconductivity, magnetism and a strange metal phase in 2D magic angle twisted bilayer graphene (MATBG), opened up novel, and highly tunable opportunities to study these mechanisms. The study of the specific heat in the quantum critical state of MATBG may help to unravel the long-standing enigma of the nature of this incoherent metallic background, the strange metal, and its relationship with the superconducting phase.

The objective of this project is to study the thermodynamics of the formation of correlated electronic phases from the so-called strange metal state. As normal transport measurement alone are insufficient to reveal these mechanisms, we will involve nanoscale thermal transport and heat capacity experiments. These techniques are based on a recently developed electronic heat capacity measurement technique for 2D materials. It is based on RF Johnson noise thermometry, that allows to directly measure the electronic temperature of the electrons while under time-resolved laser heating.