Abstract
The magnetic relaxation of isolated small (< 100 Å) monodomain magnetic particles is due to superparamagnetic relaxation (predominant at high temperatures) and eventually quantum tunneling of the magnetic moment (at low temperatures). The superparamagnetic relaxation process can be formally described by an (multiple phonon absorption and emission) Orbach process with an anisotropy Hamiltonian due to crystalline or form anisotropy \widehatIon = S2 z and a usual dynamical spin-Hamiltonian for the spin--phonon interaction. From this Mössbauer spectra can be calculated using ab-initio or stochastic methods. Phonon-assisted tunneling and its influence on Mössbauer spectra are discussed.
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References
M.L. Néel, Annales de Géophysique 5 (1949) 99.
W.F. Brown Jr., Suppl. J. Appl. Phys. 30 (1959) 130S.
W.F. Brown Jr., Phys. Rev. 170 (1963) 1677.
S. Mørup, J.A. Dumesic and D.H. Topsøe, in: Applications of Mössbauer Spectroscopy, Vol. II, ed. R.L. Cohen (Academic Press, New York, 1980) pp. 11962-53.
S. Dattagupta, G.K. Shenoy, B.D. Dunlap and L. Asch, Phys. Rev. B 16 (1977) 3893.
H.-D. Pfannes and R. Magalhães Paniago, Hyp. Interact. 83 (1994) 79.
L. Cianchi, P. Moretti, M. Mancini and G. Spina, Rep. Prog. Phys. 49 (1986) 1243.
E.C. Stoner and E.P. Wohlfarth, Philos. Trans. R. Soc. London Ser. A 240 (1948) 599; reprinted in IEEE Trans. Magn. 27 (1991) 3475.
R. Orbach and H.J. Stapleton, in: Electron Paramagnetic Resonance, ed. S. Geschwind (Plenum, New York, 1972) pp. 1211962-216.
J. Villain, F. Hartmann-Boutron, R. Sessoli and A. Rettori, Europhys. Lett. 27 (1994) 159.
A.O. Caldeira and A.J. Legett, Phys. Rev. Lett. 46 (1981) 211; Ann. Phys. 149 (1983) 374.
P.C.E. Stamp, E.M. Chudnovsky and B. Barbara, Int. J. Mod. Phys. B 6 (1992) 1355.
A. Garg, J. Appl. Phys. 76 (1994) 6168.
E.M. Chudnovsky, Phys. Rev. Lett. 72 (1994) 3433.
P. Politi, A. Rettori, F. Hartmann-Boutron and J. Villain, Phys. Rev. Lett. 75 (1995) 537.
F. Hartmann-Boutron, J. Phys. I France 5 (1995) 1281.
F. Hartmann-Boutron, J. Phys. I France 6 (1996) 137.
F. Hartmann-Boutron, P. Politi and J. Villain, Int. J. Mod. Phys. B 10 (1996) 2577.
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Pfannes, HD. Simple theory of superparamagnetism and spin-tunneling in Mössbauer spectroscopy. Hyperfine Interactions 110, 127–134 (1997). https://doi.org/10.1023/A:1012654811844
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DOI: https://doi.org/10.1023/A:1012654811844