Very large spontaneous electric polarization in BiFeO3 single crystals at room temperature and its evolution under cycling fields

TL;DR

This study reports the measurement of an exceptionally large spontaneous electric polarization in high-purity BiFeO3 single crystals at room temperature, highlighting its stability and evolution under electric cycling.

Contribution

It presents the first measurement of a record-high spontaneous polarization in bulk BiFeO3 single crystals and examines its degradation under cycling.

Findings

Spontaneous polarization reaches 100 μC/cm^2 in pure BiFeO3 crystals.

High resistivity reduces leakage currents, enabling accurate polarization measurement.

Polarization degrades with cycling, affecting hysteresis saturation.

Abstract

Electric polarization loops are measured at room temperature on highly pure BiFeO3 single crystals synthesized by a flux growth method. Because the crystals have a high electrical resistivity, the resulting low leakage currents allow us to measure a large spontaneous polarization reaching 100 microC.cm^{-2}, a value never reported in the bulk. During electric cycling, the slow degradation of the material leads to an evolution of the hysteresis curves eventually preventing full saturation of the crystals.