15 papers
Second-harmonic generation in twisted double bilayer graphene: Double-resonant enhancement from moiré flat bands
Takaaki V. Joya, Takuto Kawakami, Mikito Koshino
We theoretically investigate second-harmonic generation (SHG) in twisted double bilayer graphene (TDBG) with AB--AB and AB--BA stacking configurations using a perturbative approach…
Twist-configured moire-moire reconstruction governs diverse commensurate double-moire phases in twisted bilayer graphene on h-BN
Yuta Seo, Naoto Nakatsuji, Jimpei Kawase +6
The coexistence of multiple moire lattices in van der Waals heterostructures raises a fundamental question: how do distinct moire patterns interact and reconstruct? Here, we invest…
Ferroelectricity in a magnon Bose-Einstein condensate: Nonreciprocal superfluidity, exceptional points, and Majorana bosons
Kazuki Yamamoto, Takuto Kawakami, Mikito Koshino
We investigate a ferroelectric instability of a magnon Bose-Einstein condensate, mediated by its interaction with an electric field through a geometric Aharonov-Casher (AC) phase.…
Landau levels and magneto-optics in 30 quasi-periodic twisted bilayer graphene
Masaru Hitomi, Takuto Kawakami, Mikito Koshino
We develop a theoretical framework for Landau levels in quasi-periodic twisted bilayer graphene at a twist angle, a system without translational symmetry but possessing…
Non-Abelian Chern band in rhombohedral graphene multilayers
Taketo Uchida, Takuto Kawakami, Mikito Koshino
Moiré flat bands in rhombohedral multilayer graphene provide a platform for exploring interaction-driven topological phases, where a single isolated band often forms a Chern band.…
Resonant Structure of Second Harmonic Generation in Multilayer Graphene Polytypes
Patrick Johansen Sarsfield, Takaaki V. Joya, Takuto Kawakami +2
Second harmonic generation (SHG) is a powerful optical tool for identifying non-centrosymmetric crystalline structures. Here, we analyze SHG in multilayer graphenes (MLG), with a f…