STATIC AND DYNAMIC PROPERTIES OF MOLECULAR NANOMAGNETS INVESTIGATED BY NMR
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STATIC AND DYNAMIC PROPERTIES OF MOLECULAR NANOMAGNETS INVESTIGATED BY NMR M.Mariani 1,2 , M. Belesi 1 , H.Amiri 1 , A.Lascialfari 1,2,3 , F.Borsa 1 , P.Khuntia 1 , F. Orsini 2,3 , P. Arosio 3 , A. Cornia 4 , R. Winpenny 5 , E. Mc Innes 5 , M.Andruh 6 , P. Santini 2,7 , S. Carretta 2,7 , G. Amoretti 2,7 1 Dipartimento di Fisica “A.Volta” e Unita’ CNISM , Universita’ di Pavia, Pavia, Italy 2 S3-CNR-INFM, Modena, Italy 3 DISMAB, Universita` degli studi di Milano, Milano, Italy 4 Dipartimento di Chimica e INSTM, Università di Modena, Modena, Italy 5 Department of Chemistry, University of Manchester, Manchester, UK 6 Inorg. Chemistry Laboratory, University of Bucharest, Bucharest, Romania 7 Dipartimento di Fisica, Università degli studi di Parma, Parma, Italy
description
STATIC AND DYNAMIC PROPERTIES OF MOLECULAR NANOMAGNETS INVESTIGATED BY NMR. M.Mariani 1,2 , M. Belesi 1 , H.Amiri 1 , A.Lascialfari 1,2,3 , F.Borsa 1 , P.Khuntia 1 , F. Orsini 2,3 , P. Arosio 3 , - PowerPoint PPT Presentation
Transcript of STATIC AND DYNAMIC PROPERTIES OF MOLECULAR NANOMAGNETS INVESTIGATED BY NMR
STATIC AND DYNAMIC PROPERTIES OF
MOLECULARNANOMAGNETS
INVESTIGATED BY NMR M.Mariani1,2, M. Belesi1, H.Amiri1, A.Lascialfari1,2,3, F.Borsa1, P.Khuntia1, F. Orsini2,3, P. Arosio3,
A. Cornia4, R. Winpenny5, E. Mc Innes5, M.Andruh6, P. Santini2,7, S. Carretta2,7, G. Amoretti2,7
1Dipartimento di Fisica “A.Volta” e Unita’ CNISM , Universita’ di Pavia, Pavia, Italy2 S3-CNR-INFM, Modena, Italy
3DISMAB, Universita` degli studi di Milano, Milano, Italy4 Dipartimento di Chimica e INSTM, Università di Modena, Modena, Italy
5 Department of Chemistry, University of Manchester, Manchester, UK6 Inorg. Chemistry Laboratory, University of Bucharest, Bucharest, Romania
7 Dipartimento di Fisica, Università degli studi di Parma, Parma, Italy
The subjectThe subject
Molecular nanomagnets are organic molecules with a limited number of magnetic ions where the
intramolecular magnetic interactions are dominant over the intermolecular interaction .
Molecular nanomagnets are organic molecules with a limited number of magnetic ions where the
intramolecular magnetic interactions are dominant over the intermolecular interaction .
IDEAL MODEL SYSTEMS TO INVESTIGATE NANOMAGNETISM
IDEAL MODEL SYSTEMS TO INVESTIGATE NANOMAGNETISM
We show here three broad classes of nanomagnets showing interesting properties
and where NMR has given relevant information
We show here three broad classes of nanomagnets showing interesting properties
and where NMR has given relevant information
Phonon trapping in Ni10 Phonon trapping in Ni10 [1][1]
.The superparamagnetic
slowing down of the magnetization in Ni10
nanomagnet is not due to an anisotropy barrier ( as e.g. in
Fe8) but rather to a novel phonon trapping phenomenon as
demonstrated by the persistence of a narrow
proton NMR line even at low T
The superparamagnetic slowing down of the
magnetization in Ni10 nanomagnet is not due to an anisotropy barrier ( as e.g. in
Fe8) but rather to a novel phonon trapping phenomenon as
demonstrated by the persistence of a narrow
proton NMR line even at low T
Heterometallic ringsHeterometallic rings
Static effects [2]Static effects [2]
The redistribution of the local spin density can be probed by 53Cr NMR
in a Cr8 ring where one Cr ion is replaced by a diamagnetic Cd ion
The redistribution of the local spin density can be probed by 53Cr NMR
in a Cr8 ring where one Cr ion is replaced by a diamagnetic Cd ion
Heterometallic ringsHeterometallic rings
Dynamic effects [3,4]Dynamic effects [3,4]
1 10 100
0
1
2
3
4
5
6
1/T
1(m
s-1)
T(K)
Cr7Fe Cr7Ni The shift in the NMR
relaxation rate between the Cr7Fe and Cr7Ni is related to the different perturbation effects of the Fe and Ni ions on
the spin dynamics
The shift in the NMR relaxation rate between the Cr7Fe and Cr7Ni is related to the different perturbation effects of the Fe and Ni ions on
the spin dynamics
Single molecule paramagnets Single molecule paramagnets [5][5]
0 50 100 150 200 2502.5
2.6
2.7
2.8
2.9
3.0
T (
em
u K
/m
ol)
T(K)
Cu6Fe Exp. Fit
0 40 80 120 160
1.6
1.8
2.0
2.2
2.4
T (
em
u K
/m
ole
)
T (K)
Cu6Co Exp. Fit
The susceptibility is Curie- like down to very low temperature with
J =+0.14K in Cu6Fe and J = -1.12K in Cu6Co
The susceptibility is Curie- like down to very low temperature with
J =+0.14K in Cu6Fe and J = -1.12K in Cu6Co
Single molecule paramagnets Single molecule paramagnets [5][5]
1 10 1000.0
0.6
1.2
1.8
2.4
3.0
T1
-1_CoCu6 at 0.5T
T1
-1_FeCu6 at 1.5T
T1
-1_CoCu6 at 1.5T
T1-1
(ms-1)
T(K)
The proton NMR spin-lattice relaxation
rate is weakly T dependent down to 4K as in bulk paramagnets
The proton NMR spin-lattice relaxation
rate is weakly T dependent down to 4K as in bulk paramagnets
ReferencesReferences[1] Belesi et. al, PRL 102,177201(2009)[2] Micoti et al., PRL 97, 267204 (2006)[3] H.Amiri et al., umpublished[4] S.Carretta et al,. umpublished[5] P.Khuntia et al,.PRB 80,094413 (2009)
