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Reexamination of the microscopic couplings of the quasi one-dimensional antiferromagnet CuGeO_3

K. Fabricius·A. Klümper·U. Löw·B. Büchner·T. Lorenz
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Abstract

Experimental data for the magnetic susceptibility and magnetostriction of CuGeO_3 are analyzed within a one-dimensional antiferromagnetic model with nearest ({J_1}) and next-nearest neighbour interactions ({J_2}). We show that the ratio of the exchange constants in the antiferromagnetic chains of CuGeO_3 amounts to ${J_2}/{J_1}$ = 0.354(0.01), i.e. it is significantly larger than the critical value for the formation of a spontaneous gap in the magnetic excitation spectrum without lattice dimerization. The susceptibility data are reproduced by our numerical results over the temperature range from 20K to 950K to a high degree of accuracy for ${J_1} = 80.2 (3.0)$ and ${J_2} = 28.4 (1.8)$. The pressure dependence of the exchange constants is estimated from magnetostriction data. Furthermore, the specific heat data are checked on consistency against the calculated entropy of the above model.

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K. Fabricius, A. Klümper, U. Löw, B. Büchner, T. Lorenz. 1997-05-05. Reexamination of the microscopic couplings of the quasi one-dimensional antiferromagnet CuGeO_3. https://doi.org/10.1103/physrevb.57.1102

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