Glass-like behavior of crystalline Ge with O-impurities at low temperatures

摘要

We theoretically predict that Ge crystals with oxygen-impurity concentration = 1017-18 cm-3 show the power-law temperature dependence for specific heats C(T) T0.5 below 0.1 K. The excess specific heats stem from the correlated motion of rotating Ge2O units that yields non-trivial low-lying excitations. We also mention that the power-law behavior of C(T) in Ge:Oi can be interpreted in line with the two-level tunneling model in glasses.