# Observation of ν = 5/2 Fractional Quantum Hall Effect in Trilayer Graphene Proximitized by V‐Doped WSe2

## TL;DR

Researchers observed a rare quantum Hall effect in trilayer graphene combined with a magnetic material, which could help in developing topological quantum computing.

## Contribution

Demonstration of a high-energy-gap 5/2 fractional quantum Hall state in trilayer graphene using a V-doped WSe2 overlayer.

## Key findings

- A 5/2 fractional quantum Hall state with a large activation energy gap of 48 K was observed in trilayer graphene.
- The emergence of three additional Dirac cones, termed Dirac 'gullies,' was detected in magnetotransport measurements.
- The large energy gap enhances the feasibility of topological quantum computation by reducing error rates.

## Abstract

Graphene has long been a test bed for observing strongly correlated phenomena owing to its 2D nature and ability to host high carrier mobility. However, the lack of intrinsic magnetism and weak spin‐orbit coupling limits its ability to host strong electronic correlations. Here, observation of strongly correlated phenomena in trilayer graphene (TLG) proximitized by a ferromagnetic V‐doped WSe2 (V‐WSe2) overlayer is reported. These include the emergence of an odd‐ and even‐denominator fractional quantum Hall state at
ν
  = 5/2 and reentrant integer quantum Hall effect in the hole regime of the TLG, driven by proximate magnetism from the V‐WSe2. A remarkably large activation energy gap (Δ
5/2 = 48 ± 5 K) for the 5/2 fractional state is observed, which is essential for probing its non‐Abelian nature. Furthermore, the large Δ
5/2 significantly enhances its feasibility for topological quantum computation by exponentially suppressing the error rates. Additionally, the formation of three additional Dirac cones, termed Dirac “gullies,” is observed, which manifest as threefold‐degenerate Landau levels in magnetotransport measurements. These findings not only advance the role of magnetism in graphene‐based heterostructures but also open pathways toward studying non‐Abelian quasiparticles for their exotic fundamental and technological implications.

Even‐denominator 5/2 fractional state in trilayer graphene/V‐doped WSe2 heterostructure, mediated by proximitized magnetism, is demonstrated. An exceptionally high energy gap ∆5/2 (48 K) for the 5/2 state, significantly surpassing previous values in semiconductors and bilayer graphene (∆5/2 < 1 K) is reported. The large ∆5/2 is essential for probing the non‐Abelian nature of the 5/2 state and has implications for fault‐tolerant topological quantum computation.