Even denominator fractional quantum Hall states in the zeroth Landau level of monolayer-like band of ABA trilayer graphene.

Even-denominator fractional quantum Hall states (FQHSs) at half-filling are particularly intriguing due

to their predicted non-Abelian excitations with non-trivial braiding statistics. Conventional theory suggests

that such states primarily emerge in the first excited Landau level, a notion supported by existing exper-

imental evidence. In this research article, we present an unexpected discovery of plausibly non-Abelian

even-denominator FQHSs in the zeroth Landau level of Bernal-stacked trilayer graphene. Specifically, we

observe robust FQHSs at filling factors ν = 5/2 and ν = 7/2, accompanied by their theoretically predicted

Levin-Halperin daughter states at ν = 9/17 and ν = 7/13, respectively. Additionally, further away from

these states, the standard Jain sequence of composite fermions (CFs) is detected. The even-denominator

FQHSs and their corresponding daughter states strengthen with increasing magnetic fields, while the CF

states weaken simultaneously. Interestingly, these even-denominator (and their daughter) FQHSs only ap-

pear at a finite displacement field, precisely when two Landau levels - originating from a monolayer-like

band of trilayer graphene with distinct isospin indices - cross each other. We propose that the system’s lack

of inversion symmetry leads to additional isospin interactions, enhancing Landau level mixing between

these intersecting states and softening the short-range component of Coulomb repulsion, thereby stabilizing

the even-denominator FQHSs. Our study challenges the current theoretical framework of even-denominator

fractional quantum Hall states and expands the range of systems where they can be explored. It positions

multilayer graphene as a promising platform for hosting Majorana excitations, potentially advancing fault-

tolerant topological quantum computing.