Optical Floating Zone Growth of EuTiO3 Single Crystals: A Platform for Spin-Phonon Interaction Studies

EuTiO₃ exhibits anomalously low thermal conductivity, even at temperatures well above its Néel ordering temperature where no long-range magnetic order is present. This glasslike behavior arises from strong spin–phonon coupling between localized Eu²⁺ magnetic moments and the lattice. In EuTiO₃, next-nearest-neighbor ferromagnetic exchange interactions between Eu²⁺ spins are highly sensitive to the positions of intervening oxygen ions. Rotations and vibrations of the oxygen octahedra modulate these exchange pathways, effectively linking the lattice dynamics to the spin system. As a result, phonons are strongly scattered by spin fluctuations, leading to a significant reduction in their mean free paths and giving rise to glasslike thermal transport in an otherwise crystalline solid.

In this work, I present the growth of high-quality EuTiO₃ and SrTiO₃ single crystals using the optical floating zone technique. A comparative analysis between the magnetic (EuTiO₃) and

non-magnetic (SrTiO₃) systems will be conducted to investigate the role of spin–phonon interactions in thermal transport.