Thermodynamics and spin-tunneling dynamics in ferric wheels with excess spin

Physical Review B - Condensed Matter and Materials Physics

Volumn 64, Issue 22, 2001, Pages

  Meier, Florian ^a   Loss, Daniel ^a  

^a UNIVERSITY OF BASEL   (Switzerland)

Author keywords

[No Author keywords available]

Indexed keywords

FERRIC ION; FERRITIN;

ARTICLE; CALCULATION; ELECTRON; ELECTRON SPIN RESONANCE; MAGNET; MAGNETIC FIELD; MATHEMATICAL MODEL; MEASUREMENT; QUANTUM MECHANICS; THEORY; THERMODYNAMICS;

EID: 0001345387     PISSN: 10980121     EISSN: 1550235X     Source Type: Journal    
DOI: 10.1103/PhysRevB.64.224411     Document Type: Article

References (54)

1. I. Ya. Korenblit and E. F. Shender, Sov. Phys. JETP 48, 937 (1978).
2. E. M. Chudnovsky and L. Gunther, Phys. Rev. Lett. 60, 661 (1988).
3. Quantum Tunneling of Magnetization, edited by L. Gunther and B. Barbara (Kluwer, Dodrecht, 1994).
4. J. R. Friedman, M. P. Sarachik, J. Tejada, and R. Ziolo, Phys. Rev. Lett. 76, 3830 (1996).
5. L. Thomas, F. Lionti, R. Ballou, D. Gatteschi, R. Sessoli, and B. Barbara, Nature (London) 383, 145 (1996).
6. W. Wernsdorfer and R. Sessoli, Science 284, 133 (1999).
7. B. Barbara and E. M. Chudnovsky, Phys. Lett. A 145, 205 (1990).
8. I. V. Krive and O. B. Zaslawski, J. Phys.: Condens. Matter 2, 9457 (1990).
9. D. Gatteschi, A. Caneschi, L. Pardi, and R. Sessoli, Science 265, 1054 (1994).
10. K. L. Taft, C. D. Delfs, G. C. Papaefthymiou, S. Foner, D. Gatteschi, and S. J. Lippard, J. Am. Chem. Soc. 116, 823 (1994).
11. A. Caneschi, A. Cornia, A. C. Fabretti, S. Foner, D. Gatteschi, R. Grandi, and L. Schenetti, Chem.-Eur. J. 2, 1379 (1996).
12. O. Waldmann, J. Schülein, R. Koch, P. Müller, I. Bernt, R. W. Saalfrank, H. P. Andres, H. U. Güdel, and P. Allenspach, Inorg. Chem. 38, 5879 (1999).
13. O. Waldmann, R. Koch, S. Schromm, J. Schülein, P. Müller, I. Bernt, R. W. Saalfrank, and F. Hampel, Inorg. Chem. 40, 2986 (2001).
14. A. Chiolero and D. Loss, Phys. Rev. Lett. 80, 169 (1998).
15. B. Normand, X. Wang, X. Zotos, and D. Loss, Phys. Rev. B 63, 184409 (2001).
16. A. Cornia, A. Fort, M. G. Pini, and A. Rettori, Europhys. Lett. 50, 88 (2000).
17. J. N. S. Evans, Biomolecular NMR Spectroscopy (Oxford University Press, Oxford, 1995).
18. D. D. Awschalom, J. F. Smyth, G. Grinstein, D. P. DiVincenzo, and D. Loss, Phys. Rev. Lett. 68, 3092 (1992).
19. D. D. Awschalom, D. P. DiVincenzo, and J. F. Smyth, Science 258, 414 (1992).
20. S. Gider, D. D. Awschalom, T. Douglas, S. Mann, and M. Chaparala, Science 268, 77 (1995).
21. D. Loss, D. P. DiVincenzo, and G. Grinstein, Phys. Rev. Lett. 69, 3232 (1992).
22. J.-M. Duan and A. Garg, J. Phys.: Condens. Matter 7, 2171 (1995).
23. E. M. Chudnovsky, J. Magn. Magn. Mater. 140-144, 1821 (1995).
24. A. Chiolero and D. Loss, Phys. Rev. B 56, 738 (1997).
25. B. A. Ivanov and V. E. Kireev, JETP Lett. 69, 398 (1999).
26. D. Awschalom (private communication);A. Cornia (private communication).
27. F. Meier and D. Loss, Phys. Rev. Lett. 86, 5373 (2001).
28. R. Lü, P. Zhang, J.-L. Zhu, and L. Chang, Phys. Rev. B 56, 10 993 (1997).
29. R. Lü, H. Hu, J.-L. Zhu, X.-B. Wang, L. Chang, and B.-L. Gu, Eur. Phys. J. B 14, 349 (2000).
30. Classical spin vectors are denoted without a caret.
31. A. Cornia, A. G. M. Jansen, and M. Affronte, Phys. Rev. B 60, 12177 (1999).
32. In order to obtain reliable results for the magnetization (Formula presented) with instanton techniques, one needs anisotropies as large as (Formula presented) in (Formula presented) wheels. These values are larger than, but of the same order of magnitude as, the ones of the clusters synthesized so far.
33. Terms (Formula presented) can be neglected.
34. H. Kleinert, Path Integrals in Quantum Mechanics, Statistics, and Polymer Physics (World Scientific, Singapore, 1995).
35. (Formula presented) for (Formula presented) holds as long as (Formula presented) independent of the magnitude of (Formula presented)
36. A. Auerbach, Interacting Electrons and Quantum Magnetism (Springer, New York, 1994).
37. H.-B. Braun and D. Loss, Int. J. Mod. Phys. B 10, 219 (1996).
38. D. Loss, in Dynamical Properties of Unconventional Magnetic Systems, edited by A. T. Skjeltrop and D. Sherrington (Kluwer, Dodrecht, 1998).
39. M. Affronte, J. C. Lasjaunias, A. Cornia, and A. Caneschi, Phys. Rev. B 60, 1161 (1999).
40. The absolute value of (Formula presented) deviates from (Formula presented) by terms of order (Formula presented) which is beyond the precision of our result, Eq. (35). Hence we compare ED and analytical results only for (Formula presented) for which this shift nearly cancels.
41. Note that the classical value for (Formula presented) at the saddle points of the path integral, φ=π/2 and 3π/2, respectively, coincides with the value derived from the classical vector model in Sec. III, as it should.
42. S. Allen and D. Loss, Physica A 239, 47 (1997).
43. Terms proportional to (Formula presented) in (Formula presented) lead only to small contributions of order (Formula presented) to (Formula presented) This allows us to neglect the term (Formula presented) [Eq. (42)].
44. However, we do not claim that this is an indication that our ansatz, Eq. (26), provides a full microscopic description of the local spin directions.
45. Note that also the anisotropy energy favors a spin configuration as sketched in Fig. 33(c) such that the condition (Formula presented) can be relaxed. Consequently, also for Ga dopants a tunneling scenario is feasible.
46. J. G. E. Harris, J. E. Grimaldi, D. D. Awschalom, A. Chiolero, and D. Loss, Phys. Rev. B 60, 3453 (1999).
47. A. Garg, Europhys. Lett. 22, 205 (1993).
48. V. Yu. Golychev and A. F. Popkov, Europhys. Lett. 29, 327 (1995).
49. J. Schnack and M. Luban, Phys. Rev. B 63, 014418 (2001).
50. A. Cornia, M. Affronte, and J. Hinderer (private communication).
51. A. Lascialfari, F. Borsa, M. Horvatic, and M.-H. Julien (private communication).
52. E. M. Chudnovsky and D. A. Garanin, Phys. Rev. Lett. 87, 187203 (2001).
53. K. Park, M. A. Nowotny, N. S. Dalal, S. Hill, and P. A. Rikvold, cond-mat/0106276 (unpublished).
54. K. M. Mertes, Y. Suzuki, M. P. Sarachik, Y. Paltiel, H. Shtrikman, E. Zeldov, E. Rumberger, D. N. Hendrikson, and G. Christou, cond-mat/0106579 (unpublished).