Dielectric response of interacting oxygen defects in germanium

We theoretically demonstrate that oxygen-doped Ge crystals (Ge:O) exhibit non-trivial shallow maxima in their dielectric susceptibilities at 1 K. This anomaly originates from the dipolar interaction of rotating Ge₂O units randomly distributed in Ge:O samples. We also mention the similarity between the resulting susceptibility for Ge:O and that for mixed crystal KCl:Li observed experimentally. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)