Landau-level splitting in graphene in high magnetic fields.
The quantum Hall (QH) effect in two-dimensional electrons and holes in high quality graphene samples is studied in strong magnetic fields up to 45 T. QH plateaus at filling factors nu = 0, +/-1, +/-4 are discovered at magnetic fields B > 20 T, indicating the lifting of the fourfold degeneracy of the previously observed QH states at nu = +/-4(absolute value(n) + 1/2), where n is the Landau-level index. In particular, the presence of the nu = 0, +/-1 QH plateaus indicates that the Landau level at the charge neutral Dirac point splits into four sublevels, lifting sublattice and spin degeneracy. The QH effect at nu = +/-4 is investigated in a tilted magnetic field and can be attributed to lifting of the spin degeneracy of the n = 1 Landau level.
Zhang
Y
Y
Department of Physics and Department of Applied Physics, Columbia University, New York, New York 10027, USA.
Jiang
Z
Z
Small
J P
JP
Purewal
M S
MS
Tan
Y-W
YW
Fazlollahi
M
M
Chudow
J D
JD
Jaszczak
J A
JA
Stormer
H L
HL
Kim
P
P