Electric-Field-Induced Multiferroic Topological Solitons

Chemistry Physical Chemistry Inorganic Non-Metallic Materials Materials Science Physics Condensed Matter Physics
electric field multiferroics topological solitons thin films skyrmionics antiferromagnetic order

Concept of multiferroic topological states

Study on Electric-field-induced Multiferroic Topological Solitons in BiFeO3 Thin Films

Academic Background

Topologically protected magnetic structures in magnetic materials are predicted to be powerful tools for topological information technology. However, future magnetic soliton technology may rely more on antiferromagnetic materials due to their insensitivity to magnetic fields. Recently, complex topological objects have been discovered in intrinsic antiferromagnets, but how to efficiently control their nucleation, stabilization, and manipulation remains a significant challenge. In antiferromagnetic multiferroic materials with magnetoelectric coupling, designing topological polarization states allows for electrically writing, detecting, and erasing antiferromagnetic topological structures.

Paper Source

The paper titled “Electric-field-induced multiferroic topological solitons,” authored by Arthur Chaudron, Zixin Li, Aurore Finco, Pavel Marton, Pauline Dufour, Amr Abdelsamie, Johanna Fischer, Sophie Collin, Brahim Dkhil, Jirka Hlinka, Vincent Jacques, Jean-Yves Chauleau, Michel Viret, Karim Bouzehouane, Stéphane Fusil, and Vincent Garcia, was published in Nature Materials. The authors are from CNRS, Thales, Université Paris-Saclay, and several well-known research institutions in France and the Czech Republic.

Research Process

Overall Research Process

  1. Sample Preparation and Processing

    • BiFeO3 thin films were grown on (110)-oriented DyScO3 and SmScO3 substrates using pulsed laser deposition.
    • Nanostructures were formed by electron beam lithography and spin-coated platinum electrodes.

  2. Polarization State Writing

    • Under the action of an electric field, conductive probes of atomic force microscopy were used to write head-to-head or tail-to-tail quadrant polarization textures at the center of 800nm disc-shaped patterns.

  3. Polarization and Antiferromagnetic Structure Characterization

    • Polarization and antiferromagnetic structures were characterized using piezoelectric response force microscopy (PFM) and scanning NV magnetometry (SFM).

  4. Data Processing and Simulation

    • Polarization vector maps were generated from PFM data, and atomic spin simulations were conducted based on these data.
    • Antiferromagnetic spin field maps were derived using magnetic field simulations.

Experimental Methods and Steps

Materials and Equipment:

  • Thin Film Growth: Pulsed laser deposition using a KrF excimer laser.
  • Electrode Patterning: Electron beam lithography and sputtered platinum electrodes.
  • Central Domain Writing: Conductive probes applied the electric field to form polarization textures, with voltage settings of +50V or -50V.
  • Characterization Tools: Atomic force microscopy (Bruker Nanoscope V Multimode) and scanning NV magnetometry (Qnami Proteus Q).

Data Processing:

  • Polarization Map Generation: Polarization vector maps were extracted from PFM phase and amplitude measurements.
  • Spin Texture Simulation: Atomic spin simulations were based on the experimentally measured polarization domain maps and calibrated using NV magnetometry data.

Research Subjects

Polarization structures and corresponding antiferromagnetic spin structures formed in BiFeO3 thin films under different strains.

Research Results

Main Findings

  • Piezoelectric Response and Polarization Domains: PFM depicted the polarization central domain states under different strains. Head-to-head and tail-to-tail polarization textures formed under the electric field were clearly visible.
  • Antiferromagnetic Spin Structures: Under compressive strain, unique antiferromagnetic vortices were observed; under tensile strain, quadrant pseudo-collinear G-type antiferromagnetic arrangements were seen.
  • Simulation and Validation: Atomic spin simulation results were highly consistent with actual measurements, confirming the stability and controllability of spin textures under different polarization states.

Conclusion

This study demonstrated the formation of two distinct multiferroic topological structures in BiFeO3 thin films induced by electric fields. Under compressive strain, antiferromagnetic vortices nucleated, closely coupled with polarization central domains; under tensile strain, a quadrant pseudo-collinear G-type antiferromagnetic structure was generated. All multiferroic textures could be reversibly written by simple electrical pulses, laying the groundwork for the development of multiferroic topological memory devices.

Highlights of the Study

  • Energy-efficient Control Method: The study showcases an energy-efficient method for controlling polarization and antiferromagnetic structures via electric fields.
  • Design of Multiferroic Topological Structures: Achieved the design of multiferroic topological structures under different strains.
  • Controllability of Antiferromagnetic Spins: Precisely controlled antiferromagnetic spins using electric fields, providing new possibilities for topological information technology applications.

Significance and Value of the Study

This study not only experimentally verified the feasibility of multiferroic topological structures controlled by electric fields but also revealed the close coupling relationship between antiferromagnetic spins and polarization domains. By understanding and controlling the spin textures in BiFeO3 thin films, the research lays the foundation for developing the next generation of topological information storage devices. In the future, optimizing these multiferroic materials can lead to more efficient and stable multiferroic storage devices.