Ground-state magnetization of the molecular cluster Mn{sub 12}O{sub 12}-acetate as seen by proton NMR
Journal Article
·
· Physical Review B
{sup 1}H nuclear magnetic resonance (NMR) measurements have been carried out in Mn{sub 12}O{sub 12}-acetate clusters at low temperature in order to investigate microscopically the static and dynamic magnetic properties of the molecule in its high-spin S=10 ground state. Below liquid helium temperature it is found that the local hyperfine fields at the proton sites are static as expected for the very slow superparamagnetic relaxation of Mn{sub 12}O{sub 12} at low temperature. The magnitude and distribution of the hyperfine fields can be reproduced to a good approximation by considering only the dipolar interaction of protons with the local Mn magnetic moments and by assigning the magnitude and orientation of the local moments of the different Mn{sup 3+} and Mn{sup 4+} ions according to an accepted coupling scheme for the total S=10 ground state. The relaxation time of the macroscopic magnetization of the cluster was measured by monitoring the change of the intensity of the {sup 1}H-NMR shifted lines following inversion of the applied magnetic field. This is possible because the sudden change of the field orientation changes the sign of the shift of the NMR lines in the proton spectrum. Although important differences are noticed, the relaxation time of the magnetization as measured indirectly by the {sup 1}H-NMR method is comparable to the one obtained directly with a superconducting quantum interference device magnetometer. In particular we could reproduce the minima in the relaxation time as a function of magnetic field at the fields for level crossing, minima which are considered to be a signature of the quantum tunneling of the magnetization.
- Sponsoring Organization:
- (US)
- OSTI ID:
- 40205655
- Journal Information:
- Physical Review B, Journal Name: Physical Review B Journal Issue: 21 Vol. 62; ISSN 0163-1829
- Publisher:
- The American Physical Society
- Country of Publication:
- United States
- Language:
- English
Similar Records
NMR study of the molecular nanomagnet [Fe{sub 8}(N{sub 3}C{sub 6}H{sub 15}){sub 6}O{sub 2}(OH){sub 12}]{center_dot}[Br{sub 8}{center_dot}9H{sub 2}O] in the high-spin magnetic ground state
Magnetic structure and spin dynamics of the ground state of the molecular cluster Mn{sub 12}O{sub 12} acetate studied by {sup 55}Mn NMR
Proton NMR study of the organic metal {kappa}-(BETS){sub 2}Mn[N(CN){sub 2}]{sub 3}
Journal Article
·
Sat Sep 01 00:00:00 EDT 2001
· Physical Review B
·
OSTI ID:40277459
Magnetic structure and spin dynamics of the ground state of the molecular cluster Mn{sub 12}O{sub 12} acetate studied by {sup 55}Mn NMR
Journal Article
·
Sat Sep 01 00:00:00 EDT 2001
· Physical Review B
·
OSTI ID:40277523
Proton NMR study of the organic metal {kappa}-(BETS){sub 2}Mn[N(CN){sub 2}]{sub 3}
Journal Article
·
Mon Nov 14 23:00:00 EST 2011
· Journal of Experimental and Theoretical Physics
·
OSTI ID:22027980