Related papers: Spin tunnelling in Molecular Magnets
Spin tunneling in molecular magnets has attracted much attention, however theoretical considerations of this phenomenon up to now have not taken into account the many-spin nature of molecular magnets. We present, to our knowledge, the first…
The Landau Zener method allows to measure very small tunnel splittings \Delta in molecular clusters Fe_8. The observed oscillations of \Delta as a function of the magnetic field applied along the hard anisotropy axis are explained in terms…
The magnetic molecule Fe_8 has been observed to have a rich pattern of degeneracies in its magnetic spectrum as the static magnetic field applied to the molecule is varied. The points of degeneracy, or diabolical points in the magnetic…
The tunneling of a giant spin at excited levels is studied theoretically in mesoscopic magnets with a magnetic field at an arbitrary angle in the easy plane. Different structures of the tunneling barriers can be generated by the…
We analyze the interference between tunneling paths that occurs for a spin system with both fourth-order and second-order transverse anisotropy. Using an instanton approach, we find that as the strength of the second-order transverse…
Certain diabolical points in the tunneling spectrum of the single-molecule magnet Fe$_8$ were previously believed to be have been eliminated as a result of a weak fourth-order anisotropy. As shown by Bruno, this is not so, and the points…
Tunneling between the two lowest energy levels of single molecule magnets with Ising type anisotropy, accompanied by the emission or absorption of phonons, is considered. Quantitatively accurate calculations of the rates for such tunneling…
Intermediate spin, which occurs in the theory of anyons, can also be exhibited by mesoscopic magnetic particles. The necessary broken time reversal symmetry is due to a suitably directed magnetic field. As a function of this field a system…
The quantum tunneling of the magnetization vector are studied theoretically in single-domain ferromagnetic nanoparticles placed in an external magnetic field at an arbitrarily directed angle in the $ZX$ plane. We consider the…
The oscillation of tunnel splitting in the biaxial spin system within magnetic field along the anisotropy axis is analyzed within the particle mapping approach, rather than in the (\theta-\phi) spin coherent-state representation. In our…
We review the present state of theory and experiments on the quantum tunneling of magnetization in mesoscopic spin systems. Most attention is paid to the relaxation of magnetization in the molecular complexes Mn12 and Fe8. The role of the…
Measurements of proton NMR and the spin lattice relaxation rate 1/T1 in the octanuclear iron (III) cluster [Fe8(N3C6H15)6O2(OH)12][Br8 9H2O], in short Fe8, have been performed at 1.5 K in a powder sample aligned along the main anisotropy z…
We calculate the tunneling splittings in a Mn$_{12}$ magnetic molecule taking into account its internal many-spin structure. We discuss the precision and reliability of these calculations and show that restricting the basis (limiting the…
Strong electric fields can be used to align molecules. However, a non-polar molecule such as H$_2$ has no preference for its orientation. There are thus two equivalent configurations with equal energy separated by a potential-energy…
We measure electron tunneling via discrete energy levels in ferromagnetic cobalt particles less than 4 nm in diameter, using non-magnetic electrodes. Due to magnetic anisotropy, the energy of each tunneling resonance shifts as an applied…
The level splittings in a dimer with the antiferromagnetic coupling between two single-molecule magnets are calculated perturbatively for arbitrary spin. It is found that the exchange interaction between two single-molecule magnets plays an…
Considered is quantum tunnelling in anisotropic spin systems in a magnetic field perpendicular to the anisotropy axis. In the domain of small field the problem of calculating tunnelling splitting of energy levels is reduced to constructing…
We report measurements on magnetization reversal in the Fe$_8$ molecular magnet using fast pulsed magnetic fields of 1.5 kT/s and in the temperature range of 0.6-4.1 K. We observe and analyze the temperature dependence of the reversal…
Quantum tunneling of nano-magnets finds a natural description in terms of intermediate spin. Periodic magnetic effects correspond to a change of flux by the flux quantum $\Phi_{0}$. Schr\"odinger cat states with different superpositions of…
Coherent state path integrals are shown in general to contain instantons with jumps at the boundaries, i.e., with boundary points lying outside classical parameter or phase space. As an example, the magnetic molecule Fe_8 is studied using a…