Abstract
Abstract
The intertwined many-body correlation, nontrivial topology, and symmetry can lead to exotic low-energy quasiparticle excitation, such as fractional quantum Hall (FQH) states, Fermi liquids, etc. Some FQH states with even denominators appearing at the half-filling of Landau levels can be interpreted by Moore-Read theory, and the corresponding composite fermions satisfy non-Abelian statistics and have the potential to realize topological quantum computation. Possessing extraordinary tunability that stems from the intricate interplay of spin, valley, and orbital degrees of freedom, few-layer graphene stands out as an ideal platform for studying the FQH effect. Here we report the observation of the
ν
=
7
/
2
FQH state on the hole side of Bernal-stacked trilayer graphene unilaterally encapsulated with hexagonal boron nitride—the first realization of this state on the hole side of pristine trilayer graphene. In contrast to recently reported electron-side even-denominator states hosted in the monolayer-like
N
=
0
orbital, the
ν
=
7
/
2
state emerges in the bilayer-like
N
B
=
1
orbital near its crossing with the
N
B
=
0
level, and exhibits a transport activation gap of
Δ
tr
=
45.6
±
8.4
K, nearly two orders of magnitude larger than its electron-side counterparts. This value, obtained from Arrhenius analysis of the temperature-dependent residual resistance, is a conservative lower bound, as the analysis is limited by the residual-resistance floor. Our results suggest that few-layer graphene is an ideal platform for studying low-dimensional correlation states.