Ground-State Energy of Biquadratic Spin Systems (S=3/2) in the (1/z) 1 -Approximation
E. Błaszczak a , J. Aksamit b and A. Franek a
a Department of Medical Biophysics, Medical University of Silesia, Medyków 18, 40-752 Katowice, Poland
b Institute of Physics, Silesian University, Uniwersytecka 4, 40-007 Katowice, Poland
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Received: November 12, 2002
Corrections to the molecular-field ground-state energies of the Heisenberg model with isotropic biquadratic interactions (spin S=3/2) are calculated in the (1/z) 1 -approximation using the diagrammatic technique based on the Wick reduction theorem (z is the number of spins interacting with any given spin). The present results for the antiferri- and antiferromagnetic phases complete the previously obtained data for the antiquadrupolar, ferri- and ferromagnetic phases. From among the boundaries between different ground states only that between the antiferri- and antiferromagnetic phases is shifted with respect to its molecular-field value.
DOI: 10.12693/APhysPolA.103.403
PACS numbers: 75.10.Jm, 75.30.Ds, 75.30.Et, 75.50.Ee