https://doi.org/10.1007/s10051-001-8701-6
Independent magnon states on magnetic polytopes
1
Universität Osnabrück, Fachbereich Physik,
Barbarastr. 7, 49069 Osnabrück, Germany
2
Universität Osnabrück, Fachbereich Physik,
Barbarastr. 7, 49069 Osnabrück, Germany
Institut für theoretische Physik,
Universität Magdeburg,
PO Box 4120, 39016 Magdeburg, Germany
Corresponding author: a jschnack@uos.de
Received:
27
August
2001
Revised:
18
October
2001
Published online: 15 December 2001
For many spin systems with constant isotropic antiferromagnetic
next-neighbour Heisenberg coupling the minimal energies
form a rotational band, i.e. depend approximately
quadratically on the total spin quantum number S, a property which
is also known as Landé interval rule. However, we find that
for certain coupling topologies, including recently synthesised
icosidodecahedral structures this rule is violated for high
total spins. Instead the minimal energies are a linear function
of total spin. This anomaly results in a corresponding jump of
the magnetisation curve which otherwise would be a regular
staircase.
PACS: 75.50.Xx – Molecular magnets / 75.10.Jm – Quantized spin models / 75.40.Cx – Static properties (order parameter, static susceptibility, heat capacities, critical exponents, etc.)
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2001
