https://doi.org/10.1007/s100510050605
Theory of site-disordered magnets
1
University of Amsterdam, Van der Waals-Zeeman Institut,
Valckenierstraat 65-67, 1018 XE Amsterdam, The Netherlands
2
Institute Lorentz for Theoretical Physics, Leiden University,
P.O.B. 9506, 2300 RA Leiden, The Netherlands
Received:
27
April
1998
Revised:
27
July
1998
Accepted:
13
August
1998
Published online: 15 January 1999
In realistic spinglasses, such as ,
and
, magnetic atoms are located at random positions.
Their couplings are determined by their relative positions.
For such systems a field theory is formulated.
In certain limits it reduces to
the Hopfield model,
the Sherrington-Kirkpatrick model,
and the Viana-Bray model.
The model has a percolation transition, while for RKKY couplings
the "concentration scaling"
occurs.
Within the Gaussian approximation
the Ginzburg-Landau expansion is considered in the clusterglass phase,
that is to say, for not too small concentrations.
Near special points,
the prefactor of the cubic term, or the one of the
replica-symmetry-breaking quartic term, may go through zero. Around such points
new spin glass phases are found.
PACS: 75.10.Nr – Spin-glass and other random models / 75.30.Fv – Spin-density waves / 75.50.Lk – Spin glasses and other random magnets
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 1999