title: Probing spin correlations with phonons in the strongly frustrated magnet ZnCr2O4.
abstract: The spin-lattice coupling plays an important role in strongly frustrated magnets. In ZnCr2O4, 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 ZnCr2O4 tracks the nearest-neighbor spin correlations above T(c). The splitting of the phonon triplet below T(c) provides a way to measure the spin-Peierls order parameter.
authors.affiliation: Materials Research Science and Engineering Center, University of Maryland, College Park, Maryland 20742, USA.
authors.forename: A B
authors.initials: AB
authors.lastname: Sushkov
authors.forename: O
authors.initials: O
authors.lastname: Tchernyshyov
authors.forename: W
authors.initials: W
authors.lastname: Ratcliff
authors.forename: S W
authors.initials: SW
authors.lastname: Cheong
authors.forename: H D
authors.initials: HD
authors.lastname: Drew