Effect of internal electric field on ferroelectric polarization in multiferroic TbMnO3

Abstract

Pyro-current measurements have been widely used to study ferroelectric properties in multiferroic materials. However, determination of intrinsic polarization by this method is not straightforward because of leakage current and trapped charge carriers. Here, we demonstrate the formation of internal electric field due to thermally stimulated charge carriers and its influence on ferroelectric polarization in a polycrystalline sample of the well known multiferroic TbMnO 3 . While an electric field (E ext ) poling across the ferroelectric transition (T C ∼ 26 K) is essential to obtain depolarization current at T C , the sample poled only in the paraelectric state (T pole = 130 − 50 K) also exhibits a pyro-current peak at T C but with the same polarity (− I pyro ) as that of the external field (− E ext ).We demonstrate that these unusual behavior of pyro-current are caused by a positive internal electric field (+ E int ) which in turn is created by thermally stimulated free charge carriers during the poling process in the paraelectric state. We also show that a combination of DC-biased current and pyro-current measurements is a promising method to study the intrinsic ferroelectric properties in multiferroic materials.

Ordered aeschynite-type polar magnets RFeWO6 ( R=Dy , Eu, Tb, and Y): A new family of type-II multiferroics

“…where current was recorded with increasing temperature in the presence of applied dc -electric field without any pre-poling [27]. In Figure 5b, the temperature dependent dc-biased current measured under an applied electric field, E dc = + 9.2 kV/cm is shown.…”

“…For dc -biased current measurements, the sample was cooled to lowest temperature without any poling field. At lowest temperature, the dc electric field was applied and the current was recorded while warming the sample with a rate of 10 K/min under the electric field [27]. For all electrical measurements, contacts were made on sintered pellet samples with a high performance silver paste from Ted Pella, Inc.…”

Linear magnetoelectric effect in antiferromagnetic Sm2BaCuO5

“…To confirm further the magnetoelectric effect, we have carried out the switching of polarization and dc bias measurements. 37,38 As shown in figure 5(a), the sign of the pyrocurrent and polarization switches simultaneously with the direction of poling electric field. Moreover, we observed a strong dc bias signal with positive polarization and negative depolarization peaks under applied magnetic field at the copper ordering temperature, as shown in figure 5(b).…”

Thermally stimulated depolarization current properties of Co4Nb2O9 ceramics

“…This means that, when T Pole exceeds the valley temperature, the Maxwell‐Wagner relaxation becomes notable. Thus the high‐poling‐temperature‐induced decrease in I m for P2 can be explained as follows: A considerable internal electric field associated with P3 and P4 was generated when the poling was performed in the Maxwell‐Wagner relaxation active temperature region. The magnitude of the Maxwell‐Wagner relaxation induced internal field increases with increasing T Pole , but its direction is opposite to that of E Pole .…”