Terahertz radiation by ultrafast spontaneous polarization modulation in multiferroic BiFeO$_3$ thin films

TL;DR

This study demonstrates that ultrafast laser pulses can induce terahertz radiation in BiFeO$_3$ thin films, which directly reflects the spontaneous polarization state, enabling nonvolatile memory and domain imaging applications.

Contribution

It reveals a novel method of generating and detecting THz radiation from multiferroic BiFeO$_3$ films via ultrafast polarization modulation, with potential for memory and microscopy technologies.

Findings

THz radiation reflects spontaneous polarization state

Memory effect enables nondestructive readout

Potential for ferroelectric domain imaging

Abstract

Terahertz (THz) radiation has been observed from multiferroic BiFeO$_3$ thin films via ultrafast modulation of spontaneous polarization upon carrier excitation with illumination of femtosecond laser pulses. The radiated THz pulses from BiFeO$_3$ thin films were clarified to directly reflect the spontaneous polarization state, giving rise to a memory effect in a unique style and enabling THz radiation even at zero-bias electric field. On the basis of our findings, we demonstrate potential approaches to ferroelectric nonvolatile random access memory with nondestructive readability and ferroelectric domain imaging microscopy using THz radiation as a sensitive probe.