[qmeso-seminar] семинар 19 декабря

[Quantum Mesoscopics Dept.]

СЕМИНАР СЕКТОРА КВАНТОВОЙ МЕЗОСКОПИКИ

пятница 19 декабря, 15:00, ИТФ



Алексей Бердюгин

Making the Cleanest Graphene Ever!



The electronic quality of graphene has improved significantly over the past two decades, revealing novel phenomena.
However, even state-of-the-art devices exhibit substantial spatial charge fluctuations originating from charged defects
inside the encapsulating crystals, limiting their performance. Here, we overcome this issue by assembling devices in
which graphene is encapsulated by other graphene layers while remaining electronically decoupled from them via a large
twist angle (~10–30°). Doping of the encapsulating graphene layer introduces strong Coulomb screening, maximized by
the sub-nanometer distance between the layers, and reduces the inhomogeneity in the adjacent layer to just a few
carriers per square micrometre. The enhanced quality manifests in Landau quantization emerging at magnetic fields as low
as ~5 milli-Tesla and enables resolution of a small energy gap at the Dirac point.
Beyond large-angle graphene encapsulation, similar screening can be achieved using a graphite layer separated from
graphene by an ultrathin three-layer hBN spacer. In such devices, we observe quantum oscillations appearing already at 1
mT, carrier inhomogeneity suppressed to 10⁷ cm⁻², and transport mobilities exceeding 6 × 10⁷ cm² V⁻¹ s⁻,
surpassing those of state-of-the-art GaAs 2DEGs and establishing graphene devices with screening as the highest-mobility
material ever created.

But I will probably also speak about other our recent results, which are not that well fit into the abstract, but maybe
interesting for a public.



[Трансляция: https://zoom.us/j/96948399564?pwd=RXlKbW96Qm1tZEV6SHB0Q2JYeTdrdz09]

подробнее: http://qmeso.itp.ac.ru/seminars.php?abstract=true