The Fractional Quantum Hall to Nematic Phase transition at ν = 7/2

Recently, we observed the hydrostatic pressure-driven transition from the fractional quantum Hall state to the quantum Hall nematic phase at ν = 5/2 in the GaAs two dimensional electron system. This discovery breaks expectations about the half filled Landau level, despite thirty years of research on these filling factors. The data we obtain is consistent with a quantum phase transition from the topologically ordered fractional quantum Hall state to the broken rotational symmetry quantum Hall nematic phase. Many aspects of this transition are still unknown, however.

To study the transition in greater detail, we report now on the ν = 7/2 state under pressure. The ν = 7/2 state is the particle-hole conjugate state of ν = 5/2, and is expected to share much of the same physics. Indeed, we observe the same transition from fractional quantum Hall state to quantum Hall nematic phase at ν = 7/2. The data we obtain at ν = 7/2 is also consistent with a quantum phase transition. However, the transitions from fractional quantum Hall to quantum Hall nematic phase occur at different pressures at ν = 5/2 and ν = 7/2. We discuss the implications of this finding. This work is funded by DOE Grant DE-SC0006671.