Kenji Watanabe

Layer-polarized PN and point junctions in double bilayer graphene

We fabricate twisted double bilayer graphene devices with zero twist angle and a set of local top and bottom gates aligned perpendicularly to each other. A 1D PN junction can be electrostatically defined when the gate voltages applied to the top gates are the same but different o...

Sliding Disassembly of van der Waals Heterostructures

Abstract Many recent advances in our understanding of two-dimensional electron systems stem from van der Waals (vdW) heterostructures. The assembly process relies on the weak bonding across interfaces between layered vdW compounds, making it possible to construct exceptionally cl...

Strain Correlated Linearly Polarized Photoluminescence in WSe2/WS2 Moire Superlattices

Abstract Reliable optical control of valley degrees of freedom in moiré excitons requires that the emitted polarization faithfully reflects the underlying valley state. Here, we show that linearly polarized photoluminescence from WSe2/WS2 moiré excitons is largely insensitive t...

Entropy plateaus, combinatorial degeneracy, local moments, and heavy-fermion mass renormalization in magic-angle graphene

Abstract Heavy-fermion behavior, driven by the interaction-induced enhancement of electronic mass, underpins exotic states ranging from unconventional superconductivity to quantum criticality. Long restricted to complex three-dimensional f- electron compounds, these phenomena are...

Mid-infrared long-range surface polaritons in two-dimensional van der Waals materials

The discovery of graphene plasmons (GPs) and hyperbolic phonon polaritons (HPhPs) in two-dimensional (2D) van der Waals (vdW) materials has enabled extreme light confinement and enhanced light-matter interactions, holding the promise for miniaturized mid-infrared (mid-IR) photoni...

Robust field-free superconducting diode effect in FeTe0.55Se0.45

The superconducting diode effect (SDE), a nonreciprocal phenomenon where the critical supercurrent differs depending on the direction of current flow, is a promising foundation for superconducting logic and memory. Realizing its full potential requires a diode that operates witho...