On evaluation of transverse spin fluctuations in quantum magnets |
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Authors: | A. Singh |
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Affiliation: | (1) Department of Physics, Indian Institute of Technology, Kanpur-208016, India, IN |
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Abstract: | A numerical method is described for evaluating transverse spin correlations in the random phase approximation. Quantum spin-fluctuation corrections to sublattice magnetization are evaluated for the antiferromagnetic ground state of the half-filled Hubbard model in two and three dimensions in the whole U/t range. Extension to the case of defects in the AF is also discussed for spin vacancies and low-U impurities. In the limit, the vacancy-induced enhancement in the spin fluctuation correction is obtained for the spin-vacancy problem in two dimensions, for vacancy concentration up to the percolation threshold. For low-U impurities, the overall spin fluctuation correction is found to be strongly suppressed, although surprisingly spin fluctuations are locally enhanced at the low-U sites. Received 27 April 1998 and Received in final form 13 August 1998 |
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Keywords: | PACS. 75.10.Jm Quantized spin models - 75.10.Lp Band and itinerant models - 75.30.Ds Spin waves |
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