title: Superexchange coupling and slow magnetic relaxation in a transuranium polymetallic complex.
abstract: {Np(VI)O2Cl2}{Np(V)O2Cl(thf)3}2 is the first studied example of a polymetallic transuranic complex displaying both slow relaxation of the magnetization and effective superexchange interactions between 5f centers. The coupling constant for Np(V)-Np(VI) pairs is 10.8 K, more than 1 order of magnitude larger than the common values found for rare-earth ions in similar environments. The dynamic magnetic behavior displays slow relaxation of magnetization of molecular origin with an energy barrier of 140 K, which is nearly twice the size of the highest barrier found in polymetallic clusters of the d block. Our observations also suggest that future actinide-based molecular magnets will have very different behavior to lanthanide-based clusters.
authors.affiliation: European Commission, Joint Research Centre, Institute for Transuranium Elements, Postfach 2340, D-76125 Karlsruhe, Germany.
authors.forename: N
authors.initials: N
authors.lastname: Magnani
authors.forename: E
authors.initials: E
authors.lastname: Colineau
authors.forename: R
authors.initials: R
authors.lastname: Eloirdi
authors.forename: J-C
authors.initials: JC
authors.lastname: Griveau
authors.forename: R
authors.initials: R
authors.lastname: Caciuffo
authors.forename: S M
authors.initials: SM
authors.lastname: Cornet
authors.forename: I
authors.initials: I
authors.lastname: May
authors.forename: C A
authors.initials: CA
authors.lastname: Sharrad
authors.forename: D
authors.initials: D
authors.lastname: Collison
authors.forename: R E P
authors.initials: RE
authors.lastname: Winpenny