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arXiv · 1803.04867

Extreme field-sensitivity of the magnetic tunneling in Fe-doped Li$_3$N

M. Fix·J. H. Atkinson·P. C. Canfield·E. del Barco·A. Jesche
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Abstract

The magnetic properties of dilute Li$_2$(Li$_{1-x}$Fe$_x$)N with $x \sim 0.001$ 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 $\textit{transverse}$ magnetic fields that proves the resonant character of this tunneling process. $\textit{Longitudinal}$ fields, on the other hand, lift the ground-state degeneracy and destroy the tunneling condition. An increase of the relaxation time by four orders of magnitude in applied fields of only a few milliTesla reveals exceptionally sharp tunneling resonances. Li$_2$(Li$_{1-x}$Fe$_x$)N represents a comparatively simple and clean model system that opens the possibility to study quantum tunneling of the magnetization at liquid helium temperatures.

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M. Fix, J. H. Atkinson, P. C. Canfield, E. del Barco, A. Jesche. 2018-03-13. Extreme field-sensitivity of the magnetic tunneling in Fe-doped Li$_3$N. https://doi.org/10.1103/physrevlett.120.147202

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