The spin-reversal in dilute Li2(Li1−xFex)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 μ0H = 7 T. Magnetic dipole fields are computed numerically. Our findings affirm the absence of stoichiometric defects in Li2(Li1−xFex)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
@article{arxiv.2310.18185,
title = {Cooperative quantum tunneling of the magnetization in Fe-doped Li$_3$N},
author = {M. Fix and J. H. Atkinson and F. Müller and E. del Barco and A. Jesche},
journal= {arXiv preprint arXiv:2310.18185},
year = {2024}
}