High-temperature slow relaxation of the magnetization in Ni10 magnetic molecules.
We investigate a family of molecular crystals containing noninteracting Ni10 magnetic molecules. We find slow relaxation of the magnetization below a temperature as high as 17 K and we show that this behavior is not associated with an anisotropy energy barrier. Ni10 has a characteristic magnetic energy spectrum structured in dense bands, the lowest of which makes the crystal opaque to phonons of energy below about 1 meV. We ascribe the nonequilibrium behavior to the resulting resonant trapping of these low-energy phonons. Trapping breaks up spin relaxation paths leading to a novel kind of slow magnetic dynamics which occurs in the lack of anisotropy, magnetic interactions and quenched disorder.
Carretta
S
S
Dipartimento di Fisica, Università di Parma, I-43100 Parma, Italy.
Santini
P
P
Amoretti
G
G
Affronte
M
M
Candini
A
A
Ghirri
A
A
Tidmarsh
I S
IS
Laye
R H
RH
Shaw
R
R
McInnes
E J L
EJ