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SUMMARY:Nanoscale optics of twisted 2D materials
DTSTART:20191011T151500
DTSTAMP:20260406T064257Z
UID:dd6316cfa2f26c4a21e0493cf6131aa939835fcfd50da26f4a6fd3ea
CATEGORIES:Conferences - Seminars
DESCRIPTION:Frank Koppens ICFO – The Institute of Photonics Sciences Fra
 nk.koppens@icfo.eu\nMoiré patterns are well-known phenomena in art\, text
 iles and mathematics\, which originate\nfrom the overlay of two periodic p
 atterns. Intriguingly\, atomically thin materials can be stacked\non top o
 f each other such that a new periodic pattern can emerge: the moiré super
 lattice. This\ncan result in a dramatic modification of the electronic and
  optical properties of twisted 2D\nmaterials\, compared to those of a sing
 le layer. The moiré superlattice can give rise to a plethora\nof interest
 ing phenomena such as topological bands [1] and many-body phases like\nsup
 erconductivity and magnetism.\nA tantalizing example is twisted bilayer gr
 aphene near the magic angle (MABG)\, which exhibits\nflat superlattice min
 ibands\, effectively localizing electrons in a periodic lattice with a per
 iod of\nabout 15 nm. Several strongly correlated phases have been observed
 \, including\nsuperconductivity and the Mott-like insulating state [2].\nI
 n this talk\, we give an overview of the nano-optical properties of stacke
 d and twisted 2D\nmaterials. Nanoscale optical techniques such as near-fie
 ld optical microscopy reveal unique\nobservations of strongly confined pro
 pagating optical fields\, topological domain wall\nboundaries\, and a diff
 erent type of collective modes in charge neutral TBG near the magic angle\
 n[3].\nThe freedom to engineer these so-called optical and electronic quan
 tum metamaterials [4] is\nexpected to expose a myriad of unexpected phenom
 ena.\nReferences\n[1] Ju et al.\, Nature (2015)\n[2] Y. Cao et al. Nature 
 556\, 80 (2018)\, Cao et al. Nature 556\, 43 (2018)\n[3] Hesp et al.\, in 
 preparation\n[4] Song\, Gabor et. al.\, Nature Nanotechnology (2019)
LOCATION:CE 1 5 https://plan.epfl.ch/?room==CE%201%205
STATUS:CONFIRMED
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