Pressure Induced Compression of Flatbands in Twisted Bilayer Graphene

Bheema Lingam Chittari; Nicolas Leconte; Srivani Javvaji; Jeil Jung

doi:10.1088/2516-1075/aaead3

paper

Pressure Induced Compression of Flatbands in Twisted Bilayer Graphene

arXiv:1808.00104 · doi:10.1088/2516-1075/aaead3

Abstract

We investigate the bandwidth compression due to out of plane pressure of the moire flatbands near charge neutrality in twisted bilayer graphene for a continuous range of small rotation angles of up to $\sim 2. 5^{\circ}$ . The flatband bandwidth minima angles are found to grow linearly with interlayer coupling ω and decrease with Fermi velocity. Application of moderate pressure values of up to 2.5 GPa achievable through a hydraulic press should allow accessing a flatband for angles as large as $\sim 1.5$ ^{\circ} $in s t e a d o f$ \sim 1 \circ $a t z er o p r ess u r e . T hi sr e d u c t i o n o f t h e m o i r e ˊ p a tt er n l e n g t h f or l a r g er tw i s t an g l e im pl i es anin cr e a seo f t h ee f f ec t i v e C o u l o mbin t er a c t i o n sc a l e p er m o i r ece l l b y ab o u t 50$ \sim 2$ the elastic energy that resists the commensuration strains due to the moire pattern. Our results suggest that application of pressure on twisted bilayer graphene nanodevices through a hydraulic press will notably facilitate the device preparation efforts required for exploring the ordered phases near magic angle flatbands.

6 pages 3 figures