ISSN:
1434-6036
Keywords:
PACS. 73.43.Nq Quantum phase transitions – 75.10.Jm Quantized spin models – 75.50.Ee Antiferromagnetics
Source:
Springer Online Journal Archives 1860-2000
Topics:
Physics
Notes:
Abstract: The two-layer square lattice quantum antiferromagnet with spins 1 2 shows a zero-field magnetic order-disorder transition at a critical ratio of the inter-plane to intra-plane couplings. Adding a uniform magnetic field tunes the system to canted antiferromagnetism and eventually to a fully polarized state; similar behavior occurs for ferromagnetic intra-plane coupling. Based on a bond operator spin representation, we propose an approximate ground state wavefunction which consistently covers all phases by means of a unitary transformation. The excitations can be efficiently described as independent bosons; in the antiferromagnetic phase these reduce to the well-known spin waves, whereas they describe gapped spin-1 excitations in the singlet phase. We compute the spectra of these excitations as well as the magnetizations throughout the whole phase diagram.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s100510170052
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