Possible restoration of particle-hole symmetry in the 5/2 Quantized Hall State at small magnetic field

Abstract

Motivated by the experimental observation of a quantized 5/2 thermal conductance at filling $\nu =5/2$, a result incompatible with both the Pfaffian and the Antipfaffian states, we have pushed the expansion of the effective Hamiltonian of the $5/2$ quantized Hall state to third-order in the parameter $\kappa =E_c/\hslash {\omega }_c\propto 1/\sqrt{B}$ controlling the Landau level mixing , where $E_c$ is the Coulomb energy and ${\omega }_c$ the cyclotron frequency. Exact diagonalizations of this effective Hamiltonian show that the difference in overlap with the Pfaffian and the AntiPfaffian induced at second-order is reduced by third-order corrections and disappears around $\kappa =0.4$, suggesting that these states are much closer in energy at smaller magnetic field than previously anticipated. Furthermore, we show that in this range of $\kappa$ the finite-size spectrum is typical of a quantum phase transition, with a strong reduction of the energy gap and with level crossings between excited states. These results point to the possibility of a quantum phase transition at smaller magnetic field into a phase with an emergent particle-hole symmetry that would explain the measured $5/2$ thermal conductance of the $5/2$ quantized Hall state.

10 pages + 5 p of appendix, all comments welcome

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Cited by in corpus (3)

• Composite fermion pairing induced by Landau level mixing
• Energy minimization of paired composite fermion wave functions in the spherical geometry
• Comment on "Anomalous Reentrant 5/2 Quantum Hall Phase at Moderate Landau-Level-Mixing Strength''