Radio-frequency spectroscopy of the low-energy spectrum of the magnetic molecule Cr12 Cu2

Physical Review B - Condensed Matter and Materials Physics

Volumn 80, Issue 10, 2009, Pages

  Martin, Catalin ^a   Engelhardt, Larry ^b   Baker, Michael L ^c,d   Timco, Grigore A ^c   Tuna, Floriana ^c   Winpenny, Richard E P ^c   Tregenna Piggott, Philip L W ^e   Luban, Marshall ^a   Prozorov, Ruslan ^a  

^a IOWA STATE UNIVERSITY   (United States)

^b FRANCIS MARION UNIVERSITY   (United States)

^c UNIVERSITY OF MANCHESTER   (United Kingdom)

^d INSTITUT LAUE LANGEVIN   (France)

^e UNIVERSITY OF BERN   (Switzerland)

Author keywords

[No Author keywords available]

Indexed keywords

EID: 70349931819     PISSN: 10980121     EISSN: 1550235X     Source Type: Journal    
DOI: 10.1103/PhysRevB.80.100407     Document Type: Article

References (25)

1. O. Kahn, Molecular Magnetism (VCH, Weinheim, 1993).
2. D. Gatteschi, R. Sessoli, and J. Villain, Molecular Nanomagnets (Oxford Press, New York, 2006).
3. R. E. P. Winpenny, J. Chem. Soc. Dalton Trans. 2002, 1. 10.1039/b107118c
4. R. E. P. Winpenny, Comp. Coord. Chem. II 7, 125 (2004). 10.1016/B0-08-043748-6/06199-5
5. M. N. Leuenberger and D. Loss, Nature (London) 410, 789 (2001). 10.1038/35071024 (Pubitemid 32303771)
6. F. Meier, J. Levy, and D. Loss, Phys. Rev. Lett. 90, 047901 (2003). 10.1103/PhysRevLett.90.047901
7. F. Troiani, M. Affronte, S. Carretta, P. Santini, and G. Amoretti, Phys. Rev. Lett. 94, 190501 (2005). 10.1103/PhysRevLett.94.190501
8. L. P. Engelhardt, C. A. Muryn, R. G. Pritchard, G. A. Timco, F. Tuna, and R. E. P. Winpenny, Angew. Chem. Int. Ed. 47, 924 (2008). 10.1002/anie.200704132 (Pubitemid 351160287)
9. The full chemical formula of Cr12 Cu2 studied here is [N (C2 H5) (C3 H8) 2] 2 [Cr12 Cu2 F16 (O2 CCMe3) 26], which is a variant of compound 2 in Ref., but with the metal core planar rather than twisted. This leads to subtle variations in the exchange interactions. Using the notation of Ref., the values of the three exchange constants that we determine for the present system are J1 / kB =15.6K, J2 / kB =57.2K, and J3 / kB =-20.8K (convention: J>0 antiferromagnetic, J<0 ferromagnetic). An isotropic exchange interaction term of the form J s n s n+1 in the Heisenberg Hamiltonian links a pair of nearest-neighbor magnetic ions situated at sites n and n+1, where the spin operator s n is given in units of, and J is chosen as J1, J2, or J3 appropriate to the identities of the magnetic ions.
10. O. F. Syljuåsen and A. W. Sandvik, Phys. Rev. E 66, 046701 (2002). 10.1103/PhysRevE.66.046701 (Pubitemid 40606337)
11. L. Engelhardt, C. Martin, R. Prozorov, M. Luban, G. A. Timco, and R. E. P. Winpenny, Phys. Rev. B 79, 014404 (2009). 10.1103/PhysRevB.79.014404
12. M. Shanmugam, L. P. Engelhardt, F. K. Larsen, M. Luban, E. J. McInnes, C. A. Muryn, J. Overgaard, E. Rentschler, G. A. Timco, and R. E. P. Winpenny, Chem.-Eur. J. 12, 8267 (2006). 10.1002/chem.200600827 (Pubitemid 44759822)
13. L. Engelhardt and M. Luban, Phys. Rev. B 73, 054430 (2006). 10.1103/PhysRevB.73.054430
14. G. Cooper, G. Newton, P. Kögerler, D.-L. Long, L. Engelhardt, M. Luban, and L. Cronin, Angew. Chem., Int. Ed. 46, 1190 (2007). 10.1002/anie.200790023
15. L. Engelhardt, M. Luban, and C. Schröder, Phys. Rev. B 74, 054413 (2006). 10.1103/PhysRevB.74.054413 (Pubitemid 44232282)
16. S. T. Ochsenbein, F. Tuna, M. Rancan, R. S. G. Davies, C. A. Muryn, O. Waldmann, R. Bircher, A. Sieber, G. Carver, H. Mutka, F. Fernandez-Alonso, A. Podlesnyak, L. P. Engelhardt, G. A. Timco, H. U. Güdel, and R. E. P. Winpenny, Chem.-Eur. J. 14, 5144 (2008). 10.1002/chem.200800227
17. A. M. Todea, A. Merca, H. Bögge, T. Glaser, L. Engelhardt, R. Prozorov, M. Luban, and A. Müller, Chem. Commun. (Cambridge) 2009, 3351. 10.1039/b907188a
18. A. M. Todea, A. Merca, H. Bögge, J. van Slageren, M. Dressel, L. Engelhardt, M. Luban, T. Glaser, M. Henry, and A. Müller, Angew. Chem., Int. Ed. 46, 6106 (2007). 10.1002/anie.200700795 (Pubitemid 47290964)
19. A. Müller, A. M. Todea, J. van Slageren, M. Dressel, H. Bögge, M. Schmidtmann, M. Luban, L. Engelhardt, and M. Rusu, Angew. Chem., Int. Ed. 44, 3857 (2005). 10.1002/anie.200500697 (Pubitemid 40885693)
20. The zero-field excitation energies are calculated from the ground-state level-crossing fields using the simple fact that the zero-field energy of a given level with quantum numbers S and MS is shifted by an amount g μB H MS from its field-free value, where we use the average spectroscopic splitting factor for the system, g=2. In Fig. 4 we show how the magnetic field lifts the zero-field degeneracy of the lowest S=1, S=2, and S=3 multiplets for the present system.
21. The full list of predicted ground-state level-crossing fields (in Tesla) is 8.15, 11.9, 16.2, 19.8, 24.1, 27.6, 31.7, 35.15, 39.3, 42.6, 47.1, 50.1, 55.2, 57.65, 64.3, 65.5, and 80.7.
22. M. D. Vannette, A. Safa-Sefat, S. Jia, S. A. Law, G. Lapertot, S. L. Bud'ko, P. C. Canfield, J. Schmalian, and R. Prozorov, J. Magn. Magn. Mater. 320, 354 (2008). 10.1016/j.jmmm.2007.06.018 (Pubitemid 47625783)
23. S. Janßen, J. Mesot, L. Holitzer, A. Furrer, and R. Hempelmann, Physica B 234-236, 1174 (1997). 10.1016/S0921-4526(97)00209-3
24. L. Engelhardt, I. A. Gass, C. J. Milios, E. K. Brechin, M. Murrie, R. Prozorov, M. Vannette, and M. Luban, Phys. Rev. B 76, 172406 (2007) 10.1103/PhysRevB.76.172406
25. A. Matsuo, K. Kindo, H. Nojiri, L. Engelhardt, M. Luban, E. Brechin, and I. Gass, Phys. Rev. B 80, 092401 (2009). 10.1103/PhysRevB.80.092401