The dielectric constant of quantum paraelectric EuTiO 3 , which contains Eu 2ϩ with Sϭ7/2 spin and Ti 4ϩ , 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 change under a magnetic field ͑by ϳ7% with 1.5 T͒, 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.

No abstract

No abstract