ELFT HÍRADÓ

[Janos Asboth <asboth.janos AT ttk.bme.hu>]

Meghívó

BME Elméleti Fizika Szeminárium,

okt. 29. péntek 10h15,

1111 Budapest, Budafoki út 8., BME F III. magasföldszint 01.,
Elméleti Fizika Tanszék szemináriumi szoba

Szentpéteri Bálint (BME Fizika Tanszék):

Tailoring the band structure of twisted double bilayer graphene with
pressure

Twisted two-dimensional structures open new possibilities in band structure
engineering. In twisted graphene heterostructures, the small relative
rotation of two graphene layers changes their band structure drastically.
In twisted bilayer graphene at magic twist angles, flat bands emerge, which
give a new drive to the field of strongly correlated physics [1].
The twisted double bilayer graphene is also an interesting system with
correlated and topologically non-trivial phases. In this system the dual
gating allows changing of the Fermi level, hence the electron density, and
allows tuning the interlayer potential, giving further control over band
gaps [2,3,4].
In this talk, I show that by applying hydrostatic pressure, additional
control of the band structure becomes possible due to the tunability of
tunnel couplings between the layers [5]. The band structure can be
drastically changed by pressure, in good agreement with our simulations.
Furthermore, our measurements suggest that the pressure can decrease the
correlation effects.
[1] Cao, Y.; Fatemi, V.; Fang, S.; Watanabe, K.; Taniguchi, T.; Kaxiras,
E.; Jarillo-Herrero, P. Unconventional superconductivity in magic-angle
graphene superlattices. Nature 2018, 556, 43-50.
[2] Cao, Y.; Rodan-Legrain, D.; Rubies-Bigorda, O.; Park, J. M.; Watanabe,
K.; Taniguchi, T.; Jarillo-Herrero, P. Tunable correlated states and
spin-polarized phases in twisted bilayer-bilayer graphene. Nature 2020,
583, 215-220.
[3] He, M.; Li, Y.; Cai, J.; Liu, Y.; Watanabe, K.; Taniguchi, T.; Xu, X.;
Yankowitz, M. Symmetry breaking in twisted double bilayer graphene. Nature
Physics 2020, 17, 26-30.
[4] Liu, X.; Hao, Z.; Khalaf, E.; Lee, J. Y.; Ronen, Y.; Yoo, H.;
Najafabadi, D. H.; Watanabe, K.; Taniguchi, T.; Vishwanath, A.; Kim, P.
Tunable spin-polarized correlated states in twisted double bilayer
graphene. Nature 2020, 583, 221-225.
[5] Szentpéteri, B.; Rickhaus, P.; de Vries, F. K.; Márffy, A.; Fülöp, B.;
Tóvári, E.; Watanabe, K.; Taniguchi, T.; Kormányos, A.; Csonka, Sz.; Makk,
P. Tailoring the band structure of twisted double bilayer graphene with
pressure. Nano Letters 2021.

Minden érdeklődőt szeretettel várunk.

Asbóth János
szemináriumi koordinátor