Successive Phase Transitions from a Composite Fermion Liquid to a Fractional Quantum Hall State at ν=3/2 Driven by In-Plane Magnetic Field

Abstract: We report an even-denominator fractional quantum Hall state at ν = 3/2 induced entirely by in-plane magnetic field B_|| in an ultra-high-mobility GaAs quantum well. As B_|| increases, the system undergoes two successive transitions: from a composite fermion liquid to a soft-gap FQH state (B_||~12.2 T), then via a topological phase transition to a hard-gap robust FQH state (B_||~14.7 T), accompanied by a daughter state at ν = 19/13. We present systematic data, and discuss a possible scenario in interpreting these findings. Our work demonstrates that topological order may be engineered through k-space Fermi contour splitting under an in-plane magnetic field.