Coupling between magnetism and dielectric properties in quantum paraelectric EuTiO3 -: art. no. 054415

The dielectric constant of quantum paraelectric EuTiO3, which contains Eu2+ with S=7/2 spin and Ti4+, has been measured under a magnetic field. The dielectric constant shows a critical decrease at the antiferromagnetic ordering of the Eu spins at 5.5 K, as well as a substantial chance under a magnetic field (by similar to7% with 1.5 T), indicating a strong coupling between the Eu spins and dielectric properties. We show that the variation of the dielectric constant is dominated by the pair correlation of the nearest-neighbor Eu spins, likely via the variation of the soft-phonon-mode frequency.