Domain Wall Dynamics in Multiferroic Thin Films via Coupled Charge Transport and Scanning Probe Microscopy

Magnetoelectric multiferroic materials are a promising candidate for next-generation computation technologies due to their low-power control over coupled order parameters. While extensive efforts have been devoted to understanding their magnetoelectric coupling mechanisms and minimizing switching energy, it remains unclear whether their phase change dynamics can meet the high-frequency requirements of modern CMOS technology. Although fast intrinsic dynamics are theoretically expected, device-level experiments are often constrained by scaling limitations and circuit parasitics.

We investigate the fundamental mechanisms and high-speed dynamics of domain walls in the prototypical room-temperature magnetoelectric, BiFeO₃ (BFO). We leverage a custom-designed pulse generation circuit capable of sub-nanosecond rise times (<1 ns) and high voltage amplitudes (>100 V), in combination with scanning probe microscopy, to probe both field-limited and time-limited switching behaviors. Our methodology allows for the deterministic nucleation of single domain walls, and we observe that different domain wall types have distinct propagation dynamics: 71° domain walls exhibit coherent translational motion, while 109° domain walls propagate through more fractured, irregular pathways. Using single-shot dynamic measurements, we directly demonstrate magnetoelectric domain wall velocities reaching several kilometers per second approaching the acoustic phonon group velocity in BFO.