Electron spin relaxation of the Jahn-Teller Cu(H2O)6 complex in Cs2Zn(SO4)2•6H2O crystals

The electron spin-lattice and phase relaxation times were measured by electron spin echo (ESE) method in the temperature range 10-50 K, where Jahn-Teller dynamics of the Cu(H2O)(6) complexes is too slow to dominate in the EPR spectra of Cu2+ in Cs2Zn(SO4)(2). 6H(2)O The spin-lattice relaxation is governed by ordinary the two-phonon Raman processes which overdominate the effects expected from the Jahn-Teller dynamics. It allowed us to determine the Debye temperature of Cs2Zn(SO4)(2). 6H(2)O crystals as Theta (D) = 220 K. The ESE amplitude decay is governed by nuclear spectral diffusion below 23 K with phase memory time T-M = 5 mus. At this temperature a broadening of the lines in FT-ESE spectrum (pseudo-ENDOR spectrum) appears, and then a continuous acceleration of the phase relaxation on heating is observed. This is due to the excitations to the vibronic level of energy 71 cm(-1) in the deepest well of the potential energy surface. (C) 2001 Elsevier Science Ltd. All rights reserved.