Transition from a fractional quantum Hall liquid to an electron solid at Landau level filling ν=1/3 in tilted magnetic fields

We have observed in a low density two-dimensional hole system (2DHS) of extremely high quality (with hole density p=1.6 × 10 ¹⁰ cm ^-2 and mobility μ=0.8 × 10 ⁶ cm ²/V s) that, as the 2DHS is continuously tilted with respect to the direction of the magnetic field, the v=1/3 fractional quantum Hall effect (FQHE) state is weakened and at the temperature of ∼30 mK its magnetoresistivity rises from ∼0.4 kΩ/□ in the normal orientation to ∼180 kΩ/□ at tilt angle θ∼80°. We attribute this phenomenon to the transition from the FQHE liquid state to the pinned Wigner solid state, and argue that its origin is the strong coupling of subband Landau levels under the tilted magnetic fields.