Title: ISING-TYPE BEHAVIOUR OF CRITICAL PROPERTIES IN WEAK FERROELECTRIC Li_2Ge_7O_15
Authors: A.Yu.Kudzin, M.D.Volnianskii, M.P.Trubitsyn, I.A.Bsoul (Dnipropetrovsk State University, 13 Naukova Str., 320625 Dnipropetrovsk, Ukraine)

The dielectric constant $\varepsilon$ and electron spin resonance spectra of Mn$^{2+}$ ions have been studied in the range of the ferroelectric phase transition in Li$_2$Ge$_7$O$_{15}$ single crystals. Analysis of the experimental data permits one to estimate the critical exponents of dielectric susceptibility $\gamma\cong{}1.25$, order parameter $\beta\cong{}0.32$ and correlation length $\nu\cong{}0.63$. The values of the critical exponents determined in a fairly broad temperature interval around T$_{\rm c}$, are consistent with the theoretical predictions of the Ising model with a one-component non-polar ordering coordinate.

Comments: Figs. 3, Refs. 10, Tabs. 0.