Electron-electron (e-e) interaction is believed to be the origin of many exotic quantum phenomena in condensed matter physics. It will be helpful for us to understand the mechanism of e-e interaction if we can control its strength.
The left figure demonstrates how we control e-e interaction in 2D platform by placing an atomically-flat metallic gate (few-layer graphite) proximately to monolayer graphene separated by an atomically-thin gate dielectric (few-layer h-BN) . The title image shows the optical image of such device. The design of this device contains both vicinity and point-contact (or constriction) geometry, allowing us to use various measurements to detect e-e interaction in graphene.
By bringing the system into hydrodynamic regime, we can use viscosity measurement to detect e-e interactions which are quantitatively described by e-e scattering length. In our design, we can detect screen effect from three complementary approaches: onset fluidity from vicinity resistance , superballistic flow through constrictions , viscous hall effect in magnetohydrodynamic regime .
The technique used here can be applied to other system, such as magic-angle twisted bilayer graphene , and transition metal dichalcogenides.
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