Publikationsrepositorium - Helmholtz-Zentrum Dresden-Rossendorf

Ho₂Ti₂O₇ and Dy₂Ti₂O₇ belong to the family of rare-earth titanates with pyrochlore structure which have attracted much interest in recent years because of their spin-ice ground state and unusual magnetic excitations. Ultrasound experiments have been carried out on Ho₂Ti₂O₇ and Dy₂Ti₂O₇ at low temperatures down to 0.3 K and applied magnetic fields of up to 17.5 T. The temperature as well as field dependences of the relative change of the sound velocity demonstrate some pronounced anomalies below 2 K for the acoustic modes c₁₁ and c_L. In addition we have performed magnetization measurements of these two compounds. The observed anomalies and features in the sound velocity and magnetization provide additional information about the spin-lattice interactions in these spin-ice compounds. The role of the lattice degrees of freedom in connection with the emergent quasiparticles (magnetic monopoles) is discussed.