Radiation- and phonon-bottleneck-induced tunneling in the Fe8 single-molecule magnetM. Bal1, Jonathan R. Friedman1, W. Chen2, M. T. Tuominen3, C. C. Beedle4, E. M. Rumberger4 and D. N. Hendrickson4
1 Department of Physics, Amherst College - Amherst, MA 01002-5000, USA
2 Department of Physics and Astronomy, Stony Brook University - Stony Brook, NY 11794, USA
3 Department of Physics, University of Massachusetts - Amherst, MA 01003, USA
4 Department of Chemistry and Biochemistry, University of California at San Diego - La Jolla, CA 92093, USA
received 29 October 2007; accepted in final form 5 February 2008; published April 2008
published online 5 March 2008
We measure magnetization changes in a single crystal of the single-molecule magnet Fe8 when exposed to intense, short (20 ) pulses of microwave radiation resonant with the m = 10 to 9 transition. We find that radiation induces a phonon bottleneck in the system with a time scale of ~5 s. The phonon bottleneck, in turn, drives the spin dynamics, allowing observation of thermally assisted resonant tunneling between spin states at the 100 ns time scale. Detailed numerical simulations quantitatively reproduce the data and yield a spin-phonon relaxation time T1 ~ 40 ns.
75.45.+j - Macroscopic quantum phenomena in magnetic systems.
75.50.Xx - Molecular magnets.
76.30.-v - Electron paramagnetic resonance and relaxation.
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