Prospects for an electron electric-dipole-moment search with ferroelectric (Eu,Ba)TiO${}_3$ ceramics

We propose to use ferroelectric $(\mathrm{Eu},\mathrm{Ba}){\mathrm{TiO}}_3$ ceramics just above their magnetic ordering temperature for a sensitive electron electric-dipole-moment search. We have synthesized a number of such ceramics with various europium concentrations and measured their properties relevant for such a search: permeability, magnetization noise, and ferroelectric hysteresis loops. We also identify and estimate the likely systematics: the magnetoelectric effect, hysteresis-loop heating, and ferroelectric relaxation currents. Our measurements and estimates indicate that a search for the electron electric dipole moment with ${\mathrm{Eu}}_{0.5}{\mathrm{Ba}}_{0.5}{\mathrm{TiO}}_3$ could lead to an order of magnitude improvement on the current best limit, if the systematic effects can be controlled.

Figure 1

A schematic experimental setup for an EDM experiment.

Figure 2

XRD spectrum of Eu${}_{0.5}$Ba${}_{0.5}$TiO${}_3$ ceramic at 300 K.

Figure 3

XRD spectrum of BaTiO${}_3$ powder at 300 K.

Figure 4

The lattice constant dependence on Eu concentration in Eu${}_x$Ba${}_{1-x}$TiO${}_3$ ceramics at 300 K.

Figure 5

Eu${}_{0.5}$Ba${}_{0.5}$TiO${}_3$ conductivity as the sample is cooled down.

Figure 6

Eu${}_{0.5}$Ba${}_{0.5}$TiO${}_3$ ferroelectric hysteresis loops at 4 K (immersed in liquid helium). Different curves correspond to different frequencies of applied electric field.

Figure 7

Eu${}_{0.5}$Ba${}_{0.5}$TiO${}_3$ permeability as a function of temperature. The fit is performed using the functional form in Eq. (8).