Temperature driven anomalous unit-cell c-axis shifts in highly oriented pyrolytic graphite measured at the magic-angle

Magnetic vortex and unsaturated magnetization components in highly oriented pyrolytic graphite

“…Interestingly, presence of transitions in the c-axis of the graphitic unit-cell has been reported in multiwalled carbon nanotubes in the range from 300K to 12 K (below room temperature) [23]. Furthermore, c-axis shifts have been reported in nanostructured graphite, carbon nanotubes, carbon onions and HOPG at higher temperatures, from 298 K to 673 K [16,17,23]. However, further studies are needed in order to understand the possible relationship between such structural transitions and the magnetic correlation effects recently predicted for these systems at the magic angle.…”

“…The stacking between graphene layers and the layer orientation have been shown to play a crucial role towards modifications of band gap and energy dispersion relation characteristics of these materials. In particular, formation of unusual superconductive features in bilayer graphene and highly oriented pyrolytic graphite (HOPG) has been recently reported for specific rotational angle, known as magic angle of rotation [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. Presence of sequential stacking consisting of Bernal and rhombohedral phases has been also acknowledged as one of the possible factors governing such high temperature superconductive effects [4].…”