X-ray magnetic circular dichroism investigation of spin and orbital moments in Cr8 and Cr7Ni antiferromagnetic rings

被引：19

作者：

Corradini, V. ^{[1
,2
]}

Moro, F. ^{[1
,2
]}

Biagi, R. ^{[1
,2
]}

del Pennino, U. ^{[1
,2
]}

De Renzi, V. ^{[1
,2
]}

Carretta, S. ^{[3
]}

Santini, P. ^{[3
]}

Affronte, M. ^{[1
,2
]}

Cezar, J. C. ^{[4
]}

Timco, G. ^{[5
]}

Winpenny, R. E. P. ^{[5
]}

机构：

[1] Univ Modena & Reggio Emilia, INFM, CNR S3, Natl Res Ctr, I-41100 Modena, Italy

[2] Univ Modena & Reggio Emilia, Dipartimento Fis, I-41100 Modena, Italy

[3] Univ Parma, Dept Phys, I-43100 Parma, Italy

[4] European Synchrotron Radiat Facil, F-38043 Grenoble, France

[5] Univ Manchester, Sch Chem, Manchester M13 9PL, Lancs, England

来源：

PHYSICAL REVIEW B | 2008年 / 77卷 / 01期

关键词：

D O I：

10.1103/PhysRevB.77.014402

中图分类号：

T [工业技术];

学科分类号：

08 ;

摘要：

We investigated the electronic and magnetic properties of thick films of molecular {Cr-8} and {Cr7Ni} antiferromagnetic rings by means of x-ray absorption spectroscopy and x-ray magnetic circular dichroism (XMCD). We determined the local symmetries, the electronic configuration, and the values of orbital and spin moments at the Cr and Ni sites of the molecular rings. XMCD measurements show that the correlation between the Cr and Ni spins in the {Cr7Ni} molecular ring switches from antiferromagnetic to ferromagnetic with increasing temperature. Experimental data are interpreted using XMCD sum rules that allow the separate evaluation of the spin and the orbital contributions to the total magnetic moment of the ring as a function of temperature and magnetic field. The magnetic behaviors experimentally observed are compared with the results of spin-Hamiltonian calculations, based on microscopic parameters derived by inelastic-neutron scattering and low-temperature specific-heat measurements. The very good agreement between experimental data and calculations is a clear indication of the integrity of molecules. The temperature dependence of the ion magnetic moments results from the interplay between Zeeman and isotropic-exchange contributions, and is well captured by the theoretical model.

引用

页数：8

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