We report the observation of a resonance in the microwave spectra of the real diagonal conductivities of a two-dimensional electron system within a range of ~ +- .0.015 $ from filling factor $ u=1/3$. The resonance is remarkably similar to resonances previously observed near integer $ u$, and is interpreted as the collective pinning mode of a disorder-pinned Wigner solid phase of $e/3$-charged carriers .
Microwave pinning-mode resonances found around integer quantum Hall effects, are a signature of crystallized quasiparticles or holes. Application of in-plane magnetic field to these crystals, increasing the Zeeman energy, has negligible effect on the resonances just below Landau level filling $ u=2$, but increases the pinning frequencies near $ u=1$, particularly for smaller quasiparticle/hole densities. The charge dynamics near $ u=1$, characteristic of a crystal order, are affected by spin, in a manner consistent with a Skyrme crystal.
