Evidence on the quantum critical point in EuTiO3-SrTiO3 solid solution

Abstract

EuTiO3 (ETO) and SrTiO3 (STO) are the two well-known analogous quantum paralelectric materials. In the present study, we synthesized Eu1-xSrxTiO3 for various values of x (0 < x < 1) by solid state reaction method. X-ray diffraction (XRD) measurement performed on the synthesized samples confirmed the cubic structure with tetragonal distortion for Eu rich samples. The phase purity of the synthesized samples was also confirmed by the X-ray measurements. X-ray photoelectron spectra were measured to show that the valence state of Eu is in 2+ states. The dielectric and magnetic properties of Eu1-xSrxTiO3 samples were systematically studied. The dielectric constant against temperature for pure ETO shows sudden drop at Neel temperature 5.3 K confirming the coupling between electric and magnetic polarization. The magnetization value remains constant below the Neel temperature for ETO and Eu0.8Sr0.2TiO3 samples while others show paramagnetic behavior. The magneto dielectric effect shows a huge value of around 5% at 2 K for ETO and abruptly drops by Sr doping. The proposed phase diagram with the magnetic and dielectric data of Eu1-xSrxTiO3 suggests a quantum critical point around the composition of Eu0.7Sr0.3TiO3.