Spin-lattice relaxation of trivalent cerium, neodymium and erbium in yttrium ethyl sulfate
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spin-lattice relaxation, trivalent cerium
Spin-lattice relaxation rate measurements have been performed at Ku and X bands on trivalent cerium, neodymium and erbium ions in small concentration in an yttrium ethyl sulfate (Y(C2H5S04)309H20~ abbreviated as YES) lattice. For cerium, the main relaxation mechanism is an anisotropic resonant Raman process which appears to be phonon-limited (bottlenecked). A field dependent non-resonant Raman relaxation rate varying as H2T7sin2e is needed in order to explain our data on neopymium, but the theoretically expected strength of this process is about two orders of magnitude lower than the experimental results. This is the first reported observation of such a process. An anisotropic phonon-induced shift in the resonant field of Nd:YES was observed to vary roughly as T4. The most interesting feature of our data on erbium is probably the m dependence (where m is the expectation value of I ) of the relaxation rate z on the hyper fine lines in the direct process region. For this particular case, at X band and with the external magnetic field perpendicular to the crystal symmetry axis, the relaxation rate increases with field.
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