Glass-Like Interacting Off-Center Ca++ Dipoles As Probes Of The Coherent Quantum State In Srtio3

Anomalies in both the linear and the non-linear dielectric permittivity of weakly doped Sr1-xCaxTiO3 (x = 0.002) and strongly rising dielectric loss in the low-frequency regime evidence coupling of Ca++ centred polar nanoregions with the predicted coherent quantum state of the host lattice. Glassiness of the nanoregion system is modelled by Lacroix-Bene-type polydispersivity with an extrapolated freezing temperature T-g approximate to 4 K.