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Reentrant Spin-Peierls Transition in Mg-Doped CuGeO_3

V. Kiryukhin·Y. J. Wang·S. C. LaMarra·R. J. Birgeneau·T. Masuda·I. Tsukada·K. Uchinokura
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Abstract

We report a synchrotron x-ray scattering study of the diluted spin-Peierls (SP) material Cu_{1-x}Mg_xGeO_3. In a recent paper we have shown that the SP dimerization attains long-range order only for x < x_c = 0.022(0.001). Here we report that the SP transition is reentrant in the vicinity of the critical concentration x_c. This is manifested by broadening of the SP dimerization superlattice peaks below the reentrance temperature, T_r, which may mean either the complete loss of the long-range SP order or the development of a short-range ordered component within the long-range ordered SP state. Marked hysteresis and very large relaxation times are found in the samples with Mg concentrations in the vicinity of x_c. The reentrant transition is likely related to the competing Neel transition which occurs at a temperature similar to T_r. We argue that impurity-induced competing interchain interactions play an essential role in these phenomena.

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V. Kiryukhin, Y. J. Wang, S. C. LaMarra, R. J. Birgeneau, T. Masuda, I. Tsukada, K. Uchinokura. 1999-08-26. Reentrant Spin-Peierls Transition in Mg-Doped CuGeO_3. https://doi.org/10.1103/physrevb.61.9527

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