Zero-temperature spin-wave spectrum of the critical two-layer {ital S}=1/2 antiferromagnet
- Department of Physics, Colorado State University, Fort Collins, Colorado 80523 (United States)
Series expansions about the interlayer dimer limit are calculated to eighth order in the intralayer coupling for the {ital T}=0 antiferromagnetic susceptibility and elementary excitation spectrum of the two-layer, {ital S}=1/2, square lattice Heisenberg antiferromagnet. Extrapolations of the susceptibility and the gap series yield an estimate of the critical interlayer/intralayer coupling ratio {ital J}{sub 2}/{ital J}{sub 1}=2.54{plus_minus}0.02, in agreement with several previous numerical calculations. The spin-wave velocity at criticality is determined by an analysis of the excitation spectrum series: the result, {h_bar}{ital c}/{ital J}{sub 1}{ital a}=1.89{plus_minus}0.02, is very precise and consistent with other estimates based on numerical calculations at finite temperature. The critical spin-wave dispersion at general wave vectors is shown to deviate significantly from a uniformly renormalized mean-field spectrum. {copyright} {ital 1996 The American Physical Society.}
- OSTI ID:
- 283872
- Journal Information:
- Physical Review, B: Condensed Matter, Vol. 53, Issue 17; Other Information: PBD: May 1996
- Country of Publication:
- United States
- Language:
- English
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