https://doi.org/10.1140/epjb/e2005-00146-y
EPR spectrum via entangled states for an exchange-coupled dimer of single-molecule magnets
1
Institute of Theoretical Physics, Shanxi University, Taiyuan 030006,
China
2
Department of Physics, Linyi Normal University, Shandong Linyi
276005, China
and
Department of Physics, Qufu Normal University, Shandong Qufu
273165, China
Corresponding author: a xuchangtan@yahoo.com.cn
Received:
21
October
2004
Published online:
30
May
2005
Multi-high-frequency electron paramagnetic resonance(EPR) spectrum for a
supermolecular dimer of single-molecule magnets
recently reported [S. Hill, R.S. Edwards, N. Aliaga-Alcalde and G.
Christou (HEAC), Science 302, 1015 (2003)] is studied in terms of the
perturbation method in which the high-order corrections to the level
splittings of degenerate states are included. It is shown that the
corresponding eigenvectors are composed of entangled states of two
molecules. The EPR-peak positions are calculated in terms of the eigenstates
at various frequencies. From the best fit of theoretical level splittings
with the measured values we obtain the anisotropy constant and exchange
coupling which are in agreement with the corresponding values of
experimental observation. Our study confirms the prediction of HEAC that the
two Mn4 units within the dimer are coupled quantum mechanically by the
antiferromagnetic exchange interaction and the supermolecular dimer
behaviors in analogy with artificially fabricated quantum dots.
PACS: 75.45.+j – Macroscopic quantum phenomena in magnetic systems / 75.50.Xx – Molecular magnets / 75.50.Tt – Fine-particle systems; nanocrystalline materials
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2005