Effect of point defect concentration in NaCl and LiF crystals on the saturation field of the magnetoplastic effect

The effect is studied of the calcium impurity concentration in NaCl crystals and of preliminary x-ray irradiation of NaCl and LiF crystals on the magnetic saturation field B₀ characterizing the transition from the conventional proportionality of the dislocation mean path length l to the magnetic induction B squared(l∝B²) to saturation (l=const). B₀ is shown to increase with the calcium concentration in NaCl crystals and with the dose of x-ray irradiation of NaCl and LiF. This finding indicates that the dislocation breakaway from local defects in weak magnetic fields is controlled by the mechanism of longitudinal spin relaxation in a system of radical pairs that form due to interaction between dislocation cores and paramagnetic centers.