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arXiv · 2310.18185

Cooperative quantum tunneling of the magnetization in Fe-doped Li$_3$N

M. Fix·J. H. Atkinson·F. Müller·E. del Barco·A. Jesche
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Abstract

The spin-reversal in dilute Li$_2$(Li$_{1-x}$Fe$_{x}$)N with $x < 1$ % is dominated by resonant quantum tunneling of spatially well-separated states. We report on the effect of finite couplings between those states that give rise to cooperative, simultaneous quantum tunneling of two spins. This phenomenon, known as spin-spin cross relaxation, effectively elucidates the fine-structure observed in isothermal magnetization loops, a previously unresolved aspect. Temperature and field-dependent magnetization measurements were conducted over a range from T = 2 K to 300 K in applied fields of up to $\mu_0H$ = 7 T. Magnetic dipole fields are computed numerically. Our findings affirm the absence of stoichiometric defects in Li$_2$(Li$_{1-x}$Fe$_{x}$)N and underscore its exemplary suitability as a model system for investigating spin-reversal processes at the microscopic level. This is attributed to its comparatively simple crystal structure, the availability of large single crystals, elevated characteristic energies, and well-defined energy levels

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M. Fix, J. H. Atkinson, F. Müller, E. del Barco, A. Jesche. 2023-10-27. Cooperative quantum tunneling of the magnetization in Fe-doped Li$_3$N. https://doi.org/10.1103/physrevb.110.134405

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