Order-disorder and central peak behavior in SrTiO3

Abstract

Abstract Recent detailed Electron Paramagnetic Resonance (EPR) studies will be presented which gave insight into the central peak phenomenon concerning its width and intensity. The studies were conducted with the Fe3+ - Vo center in a monodomain single crystal of SrTiO3, for Tc ≤ T < 295 K.1 From the angular dependence of the observed width, an upper limit of 6 MHz is placed upon the characteristic frequency of the local rotation fluctuations between Tc < T < Tc + 11K. The characteristic collective-mode relaxation rate, i.e., the “central-peak” width, should be about an order of magnitude narrower. A comparison of its narrow width with existing computer simulations2 above Tc indicates that the width of the c.p. has extrinsic origin, i.e., is impurity dominated.