Phys Rev Lett. 2001 Aug 27;87(9):097205. doi: 10.1103/PhysRevLett.87.097205. Epub 2001 Aug 14.
Physical review letters
J J Alonso, J F Fernández
PMID: 11531597 DOI: 10.1103/PhysRevLett.87.097205
We have performed Monte Carlo simulations of interacting dipoles that relax through quantum tunneling. We aim to mimic tunneling experiments on crystals of magnetic clusters, such as Fe(8), at very low temperatures. Accordingly, we allow spin flips only if the corresponding energy change is less than some 2 delta h(hf). Time evolutions of the dipolar field distribution P(t)(H) are studied. As in experiments, a "hole" develops in P(t)(H). The half-width W of incipient holes of weakly polarized systems are, under certain conditions, simply related to delta h(hf). For k(B)T less than approximately 0.5 delta h(hf) and delta h(hf) smaller than approximately 1/10 of the half-width of the dipolar field distributions of disordered systems, W approximately equal to 0.75 delta h(hf).
