Nuclear Spin-Lattice Relaxation Of (Brfe)-Br-82

The field dependence of the nuclear spin-lattice relaxation (SLR) of cold implanted Br-82 (T <= 25 rnK) in alpha-Fe single crystals was investigated With nuclear magnetic resonance of oriented nuclei (NMR/ON) at low temperatures as experimental technique. The SLR at the lattice sites with the hyperfine fields found by earlier NMR/ON experiments was measured as a function of the applied external magnetic field B-est parallel to the three principle axes [100], [110] and [111] of the iron single crystal. The data were evaluated with the full relaxation formalism in the single impurity limit and for comparison also with the often employed model of a single exponential function with,in effective relaxation time T-1'. With a phenomenological model the high field values of the relaxation rates r(infinity,[100]') = 6.6(2) . 10(-15) T(2)sK(-1), r(infinity,[110]) = 5.4(2) . 10(-15) T(2)sK(-1) and r(infinity,[111]) = 5.2(1) . 10(-15) T(2)sK(-1) were obtained.