  The multiferroic properties of EuTiO3 are greatly enhanced when a sample is
strained, signifying that coupling between strain and structural, magnetic or
ferroelectric order parameters is extremely important. Here resonant ultrasound
spectroscopy has been used to investigate strain coupling effects, as well as
possible additional phase transitions, through their influence on elastic and
anelastic relaxations that occur as a function of temperature between 2 and 300
K and with applied magnetic field up to 14 T. Antiferromagnetic ordering is
accompanied by acoustic loss and softening, and a weak magnetoelastic effect is
also associated with the change in magnetization direction below ~2.8 K.
Changes in loss due to the influence of magnetic field suggest the existence of
magnetic defects which couple with strain and may play a role in pinning of
ferroelastic twin walls.
