Non-Arrhenius threshold switching by field-driven dipolar ordering

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Amorphous chalcogenides present challenges for memory technologies due to structural disorder.
• Understanding the atomic-scale threshold switching mechanism is crucial for developing advanced memory devices.

Purpose of the Study:

• To resolve the atomic-scale threshold switching mechanism in amorphous chalcogenides.
• To demonstrate electric-field-driven dipolar ordering in amorphous GeSe.
• To enable atomic-scale dipole control for ultrafast storage-class memory.

Main Methods:

• Combined atomic-resolution angstrom-beam electron diffraction.
• Field-coupled ab initio molecular dynamics simulations.
• Analysis of electric-field-induced atomic displacements and dipole alignment.

Main Results:

• Electric fields induce anti-parallel atomic displacements in GeSe within picoseconds, aligning dipoles into one-dimensional chains.
• Polarity-locked chains, evidenced by specific diffraction spots, guide conductive filament growth.
• Threshold voltage asymmetry is harnessed for selector-only memory with dual functionality.
• Field-induced switching occurs within the picosecond regime, surpassing thermal speed limits.

Conclusions:

• Atomic-scale dipole ordering is the key mechanism for threshold switching in amorphous GeSe.
• This mechanism allows for the engineering of ultrafast, selector-only memory devices.
• The findings provide a pathway for controlling atomic dipoles for next-generation storage-class memory.