External bias dependent dynamic terahertz propagation through BiFeO₃film

Area of Science:

• Condensed Matter Physics
• Materials Science
• Photonics

Background:

• Terahertz (THz) radiation offers diverse applications but is limited by a lack of responsive materials.
• Multiferroic materials, like BiFeO3, show promise for novel THz device functionalities.

Purpose of the Study:

• To investigate the interaction of terahertz radiation with multiferroic BiFeO3 thin films under applied electric fields.
• To explore the potential of BiFeO3 as a dynamic material for THz applications.

Main Methods:

• Terahertz time-domain spectroscopy (THz-TDS) was employed to study a ~200 nm BiFeO3 film.
• Vertically applied electric fields (0-600 kV cm-1) were used to probe material response.
• Switching spectroscopy piezoresponse force microscopy (SS-PFM) was used for comparison.

Main Results:

• Dynamic modulation of THz amplitude by up to 7% was observed in the 0.2-1 THz range.
• Hysteretic polarization switching in BiFeO3 was detected non-contactedly via THz-TDS.
• Results correlated with SS-PFM measurements, indicating domain alignment affects THz transmission.

Conclusions:

• Electric-field-induced polarization switching in BiFeO3 modulates THz transmission by altering scattering losses and refractive index.
• This demonstrates the potential for integrating nanoscale multiferroics into THz photonics for dynamic device functionalities.
• The findings open avenues for developing next-generation THz devices with tunable properties.