Mössbauer‐Effect Study of Erbium Spin Relaxation in Magnetically Ordered Compounds

The 166Er hyperfine fields, Er3+ magnetic moments, and electronic spin correlation times in ferromagnetic erbium‐aluminum intermetallic structures have been studied between 1.5° and 80°K using the Mossbauer effect of the 80.6 keV gamma rays of 166Er. The spin correlation times deduced from both the rate equation model and the Wegener formula follow approximately a T−1 temperature dependence below TC. Above TC the spin correlation times of about 5 × 10−11 sec decrease by nearly an order of magnitude and are found to be rather sensitive to the distinct assumptions made on the electronic ground‐state multiplet and attributed Sz distribution function in the different theoretical approaches.