Quantum liquid versus electron solid around ν=1/5 Landau-level filling

Abstract

In the high-magnetic-field low-disorder limit the ground state at \ensuremath{\nu}=1/5 Landau-level filling is an incompressible quantum liquid. This is determined by observing vanishing resistivity ${\mathrm{\ensuremath{\rho}}}_{\mathit{x}\mathit{x}}$ as the temperature T\ensuremath{\rightarrow}0. At filling factors below \ensuremath{\nu}=1/5 as well as in a narrow region above \ensuremath{\nu}=1/5, ${\mathrm{\ensuremath{\rho}}}_{\mathit{x}\mathit{x}}$ diverges exponentially as T\ensuremath{\rightarrow}0. This contrasts the T dependence at any higher \ensuremath{\nu}. We conclude that the quantum liquid at \ensuremath{\nu}=1/5 is surrounded by a different phase. In as much as the exponential divergencies are indicative of an electron solid this phase is reentrant in a narrow region above \ensuremath{\nu}=1/5.