Spin-Echo Measurement of the Spin-Lattice and Spin-Spin Relaxation inCe3+in Lanthanum Magnesium Nitrate

Fast-resolution time-pulsed microwave apparatus has been used to measure the spin-spin and spin-lattice relaxation in ${\mathrm{Ce}}^{3+}$ in lanthanum magnesium nitrate by spin-echo techniques. $T_1$, measured by a three-pulse sequence, varies as $T_1=6\mathrm{}\times {10}^{-10\mathrm{}}\exp \left(\frac{34}{T}\right)$ over a range of four orders of magnitude from 4°K to 1.8°K but changes less rapidly below this temperature. $T_2$, measured by the decay of the echo following a two-pulse sequence, is approximately 1 μsec at 1.4°K and drops very rapidly above 3°K.