Ames Laboratory; Physics and Astronomy
Physics and Astronomy, Ames Laboratory
Physical Review Letters
The magnetic properties of dilute Li-2(Li1-xFex)N with x similar to 0.001 are dominated by the spin of single, isolated Fe atoms. Below T = 10 K the spin-relaxation times become temperature independent indicating a crossover from thermal excitations to the quantum tunneling regime. We report on a strong increase of the spin-flip probability in transverse magnetic fields that proves the resonant character of this tunneling process. Longitudinal fields, on the other hand, lift the ground-state degeneracy and destroy the tunneling condition. An increase of the relaxation time by 4 orders of magnitude in applied fields of only a few milliTesla reveals exceptionally sharp tunneling resonances. Li-2(Li1-xFex)N represents a comparatively simple and clean model system that opens the possibility to study quantum tunneling of the magnetization at liquid helium temperatures.
Department of Energy Subject Categories
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS
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