Magnetic field effects on the far-infrared absorption inMn12-acetate

Abstract

We report the far-infrared spectra of the molecular nanomagnet Mn12-acetate (Mn12) as a function of temperature (5-300 K) and magnetic field (0-17 T). The large number of observed vibrational modes is related to the low symmetry of the molecule, and they are grouped together in clusters. Analysis of the mode character based on molecular dynamics simulations and model compound studies shows that all vibrations are complex; motion from a majority of atoms in the molecule contribute to most modes. Three features involving intramolecular vibrations of the Mn12 molecule centered at 284, 306 and 409 cm −1 show changes with applied magnetic field. The structure near 284 cm −1 displays the largest deviation with field and is mainly intensity related. A comparison between the temperature dependent absorption difference spectra, the gradual low-temperature cluster framework distortion as assessed by neutron diffraction data, and field dependent absorption difference spectra suggests that this mode may involve Mn motion in the crown.

Quantum dynamics of crystals of molecular nanomagnets inside a resonant cavity

“…Such a large angular momentum is almost classical. Still crystals of Mn 12 and Fe 8 exhibit spectacular magnetic effects related to the quantization and quantum tunneling of the angular momentum. The present interest of physicists in these systems was ignited by the discovery of the quantum stepwise magnetic hysteresis in Mn 12 acetate.…”

“…Still crystals of Mn 12 and Fe 8 exhibit spectacular magnetic effects related to the quantization and quantum tunneling of the angular momentum. The present interest of physicists in these systems was ignited by the discovery of the quantum stepwise magnetic hysteresis in Mn 12 acetate. 2 Steps of quantum nature in the magnetization curve of magnetic clusters and single ions have been seen in the past.…”

“…1 The discovery of high-spin molecular nanomagnets has given a strong boost to that field. The most carefully studied nanomagnets are Mn 12 and Fe 8 molecular clusters. Both have spin 10, which is 20 times the spin of electron.…”

Superradiance from Crystals of Molecular Nanomagnets

“…Recent ESR experiments [17,18,19,20,21] have demonstrated noticeable resonant absorption of electromagnetic radiation by molecular magnets. In this Letter we show that crystals of magnetic molecules can also be a powerful source of coherent electromagnetic radiation.…”

“…The lifetime of these states is believed to be dominated by spin-phonon processes [3,4] and by quantum spin tunneling [5,6,7,8]. The latter, for a field-sweep experiment, has been successfully described in terms of single-molecule Landau-Zener (LZ) transitions [9,10,11,12,13,14,15,16].Recent ESR experiments [17,18,19,20,21] have demonstrated noticeable resonant absorption of electromagnetic radiation by molecular magnets. In this Letter we show that crystals of magnetic molecules can also be a powerful source of coherent electromagnetic radiation.…”