How systems of single-molecule magnets magnetize at low temperatures

Details How systems of single-molecule magnets magnetize at low temperatures How systems of single-molecule magnets magnetize at low temperatures

2003-12-24

arxiv.org/abs/cond-mat/0312627v1

Phys.Rev B v69, 024411 (2004)

Physics

Condensed Matter

Statistical Mechanics

11 LaTeX pages, 8 figures. Submitted to PRB on 5 September 2003. Accepted on 30 October 2003

Scientific paper

10.1103/PhysRevB.69.024411

We model magnetization processes that take place through tunneling in crystals of single-molecule magnets, such as Mn_12 and Fe_8. These processes take place when a field H is applied after quenching to very low temperatures. Magnetic dipolar interactions and spin flipping rules are essential ingredients of the model. The results obtained follow from Monte Carlo simulations and from the stochastic model we propose for dipole field diffusion. Correlations established before quenching are shown to later drive the magnetization process. We also show that in simple cubic lattices, m \propto sqrt(t) at time t after H is applied, as observed in Fe_8, but only for 1+2\log_10(h_d/h_w) time decades, where h_d is some near-neighbor magnetic dipolar field and a spin reversal can occur only if the magnetic field acting on it is within some field window (-h_w,h_w). However, the sqrt(t) behavior is not universal. For BCC and FCC lattices, m \propto t^p, but p \simeq 0.7 . An expression for p in terms of lattice parameters is derived. At later times the magnetization levels off to a constant value. All these processes take place at approximately constant magnetic energy if the annealing energy epsilon_a is larger than the tunneling window's energy width (i.e., if epsilon_a \gtrsim g\mu_B h_w S). Thermal processes come in only later on to drive further magnetization growth.

Affiliated with

Also associated with

No associations

Rating

How systems of single-molecule magnets magnetize at low temperatures does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with How systems of single-molecule magnets magnetize at low temperatures, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and How systems of single-molecule magnets magnetize at low temperatures will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-640595