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arXiv · 1305.5405

Magnetoelastic excitations in the pyrochlore spin liquid Tb$_2$Ti$_2$O$_7$

T. Fennell·M. Kenzelmann·B. Roessli·H. Mutka·J. Ollivier·M. Ruminy·U. Stuhr·O. Zaharko·L. Bovo·A. Cervellino·M. K. Haas·R. J. Cava
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Abstract

At low temperatures, Tb$_2$Ti$_2$O$_7$ enters a spin liquid state, despite expectations of magnetic order and/or a structural distortion. Using neutron scattering, we have discovered that in this spin liquid state an excited crystal field level is coupled to a transverse acoustic phonon, forming a hybrid excitation. Magnetic and phononlike branches with identical dispersion relations can be identified, and the hybridization vanishes in the paramagnetic state. We suggest that Tb$_2$Ti$_2$O$_7$ is aptly named a "magnetoelastic spin liquid" and that the hybridization of the excitations suppresses both magnetic ordering and the structural distortion. The spin liquid phase of Tb$_2$Ti$_2$O$_7$ can now be regarded as a Coulomb phase with propagating bosonic spin excitations.

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T. Fennell, M. Kenzelmann, B. Roessli, H. Mutka, J. Ollivier, M. Ruminy, U. Stuhr, O. Zaharko, L. Bovo, A. Cervellino, M. K. Haas, R. J. Cava. 2014-01-15. Magnetoelastic excitations in the pyrochlore spin liquid Tb$_2$Ti$_2$O$_7$. https://doi.org/10.1103/physrevlett.112.017203

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