Spin-lattice coupling induced crossover from negative to positive magnetostriction in ${\mathrm{EuTiO}}_3$

Magnetostriction experiments have been performed at temperatures in and above the antiferromagnetic phase of ${\mathrm{EuTiO}}_3$. For magnetic fields below the spin-flop transition the magnetostriction is large and negative and changes to small and positive for fields exceeding this threshold. At the antiferromagnetic phase transition temperature a steep anomaly in the thermal expansion is observed in zero field which broadens and moves to lower temperature with increasing field strength. A small but well resolved anisotropy in the longitudinal and transverse field configurations of the magnetostriction is observed at low temperatures, which rapidly vanishes with increasing temperature. The crossover field where the magnetostriction changes sign coincides with the field strength where the dielectric constant adopts normal quantum paraelectric behavior and signifies strong magnetoelectric coupling to be its origin.

Figure 1

Temperature and magnetic field dependence of the magnetization of ETO.

Figure 2

Phase diagram of ETO as a function of field and temperature. The full circles have been obtained from the field derivative of the data shown in Fig. 1 and the maximum in the thermal expansion coefficient shown in Fig. 4. The inset in the lower left corner shows the magnetic susceptibility of ETO and the inset in the upper right corner displays the low-temperature specific heat of ETO.

Figure 3

Relative length change as a function of temperature at different magnetic fields for ETO.

Figure 4

Magnetic field dependence of the average linear coefficient of thermal expansion.

Figure 5

Anisotropy ratio γ of ETO as a function of magnetic field for representative temperatures.