Tuning the Multiferroic Properties of BiFeO_{3} under Uniaxial Strain

Area of Science:

• Condensed Matter Physics
• Materials Science
• Magnetism and Ferroelectricity

Background:

• Multiferroic compounds, combining magnetism and ferroelectricity, have garnered significant interest.
• Bismuth ferrite (BiFeO3) is a prominent room-temperature multiferroic with desirable properties like electromagnons and conductive domain walls.
• Previous strain engineering of BiFeO3 properties was limited to thin films and substrate-dependent lattice parameters.

Purpose of the Study:

• To investigate the ferroelectric and dynamic magnetic response of BiFeO3 bulk under continuously tunable uniaxial strain.
• To explore how varying strain levels influence the material's multiferroic properties.
• To understand the interplay between ferroelectric and magnetic orders under mechanical stress.

Main Methods:

• Elasto-Raman spectroscopy was employed to probe the ferroelectric soft mode and magnonic response.
• Continuously tunable uniaxial strain was applied to BiFeO3 bulk samples.
• Effective Hamiltonian calculations were performed to model the observed phenomena.

Main Results:

• Tensile strain significantly enhances the ferroelectric soft mode, driven by volume-preserving deformation at low strains.
• The magnonic response is altered, with low-energy magnon modes suppressed under tensile strain, indicating a transition from cycloidal to homogeneous magnetic order.
• Effective Hamiltonian calculations confirm competition between ferroelectric and antiferrodistortive modes under tensile strain.
• A homogeneous antiferromagnetic state becomes more stable than the cycloidal state above +2% tensile strain.

Conclusions:

• Uniaxial strain provides a powerful tool to tune the multiferroic properties of BiFeO3.
• Tensile strain can selectively enhance ferroelectricity and modify the magnetic structure, unlocking differentiated control over polarization and magnetic ordering.
• The findings pave the way for novel applications in magnonic devices and strain-engineered multiferroics.