Glass transition in CDW system o-TaS3

We report on the experimental evidence of a glass transition in the CDW phase of orthorhombic TaS3 at Tg ~ 50 K, brought by means of dielectric constant measurement. The relaxational mode exhibits in this T-range a critical slowing down instead of an expected activated behavior. New processes appear below the glass transition temperature which we attribute to the defect dynamics. There is an apparent similarity with the scenario of freezing out in supercooled liquids. However, the peculiarity of this glass transition is a very large length scale of order of μm (beyond the phase coherence length of the underlying CDW), compared to nm in supercooled liquids.