Abstract:
In the present paper, we study the magnetic properties of bilayer cuprate antiferromagnets. In order to evaluate the expressions for spin-wave dispersion, sublattice magnetization, Néel temperature and the magnetic contribution to the specific heat, the double time Green's function technique has been employed in the random phase approximation (RPA). The spin wave dispersion curve for a bilayer antiferromagnetic system is found to consist of one acoustic and one optic branch. The “optical magnon gap” has been attributed solely to the intra-bilayer exchange coupling (J ⊥ ) as its magnitude does not change significantly with the inter-bilayer exchange coupling (Jz). However Jz is essential to obtain the acoustic mode contribution to the magnetization. The numerical calculations show that the Néel temperature (T N ) of the bilayer antiferromagnetic system increases with the Jz and a small change in Jz gives rise to a large change in the Néel temperature of the system. The magnetic specific heat of the system follows a T2 behaviour but in the presence of Jz it varies faster than T2.
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Received 13 July 2000 and Received in final form 14 May 2001
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Govind, Pratap, A., Ajay et al. Magnetic properties of undoped YBa 2 Cu 3 O 6 + x system. Eur. Phys. J. B 23, 153–158 (2001). https://doi.org/10.1007/s100510170062
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DOI: https://doi.org/10.1007/s100510170062