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Probing spin correlations with phonons in the strongly frustrated magnet ZnCr2O4

A. B. Sushkov·H. D. Drew·O. Tchernyshyov·W. Ratcliff II·S. W. Cheong
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Abstract

The spin-lattice coupling plays an important role in strongly frustrated magnets. In ZnCr$_2$O$_4$, an excellent realization of the Heisenberg antiferromagnet on the ``pyrochlore'' network, a lattice distortion relieves the geometrical frustration through a spin-Peierls-like phase transition at $T_c = 12.5$ K. Conversely, spin correlations strongly influence the elastic properties of a frustrated magnet. By using infrared spectroscopy and published data on magnetic specific heat, we demonstrate that the frequency of an optical phonon triplet in ZnCr$_2$O$_4$ tracks the nearest-neighbor spin correlations above $T_c$. The splitting of the phonon triplet below $T_c$ provides a way to measure of the spin-Peierls order parameter.

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A. B. Sushkov, H. D. Drew, O. Tchernyshyov, W. Ratcliff II, S. W. Cheong. 2004-12-14. Probing spin correlations with phonons in the strongly frustrated magnet ZnCr2O4. https://doi.org/10.1103/physrevlett.94.137202

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