No abstract

No abstract

No abstract

Dielectric measurements at very low temperature indicate that in a glass with the eutectic composition BaO-Al2O3-SiO2 a phase transition occurs at 5.84 mK. Below that temperature small magnetic fields of the order of 10 µT cause noticeable changes of the dielectric constant although the glass is insensitive to fields up to 20 T above 10 mK. The experimental findings may be interpreted as the signature of the formation of a new phase in which many tunneling systems perform a coherent motion resulting in a macroscopic wave function.

No abstract