Coherent Electron Spin Precession Enabled by Ultrafast Hole Transfer in Type-II Two-Dimensional Perovskites

Area of Science:

• Materials Science
• Quantum Physics
• Spintronics

Background:

• Two-dimensional (2D) lead halide perovskites are promising for quantum and spintronic devices.
• Short spin lifetimes (subpicosecond) due to electron-hole exchange limit their application.
• Extending spin lifetime and achieving coherent spin precession are key challenges.

Purpose of the Study:

• To investigate spin relaxation and precession dynamics in type-II 2D perovskites with carbazole-based organic spacers.
• To overcome the limitations of short spin lifetimes in 2D perovskites.
• To explore the potential for coherent spin manipulation in these materials.

Main Methods:

• Fabrication of type-II 2D perovskites with carbazole organic spacers.
• Ultrafast spectroscopy to study spin relaxation and precession dynamics.
• Temperature-dependent measurements to analyze phonon scattering effects.

Main Results:

• Achieved an electron spin lifetime of 40 picoseconds at room temperature, a 200-fold increase.
• Extended spin lifetime to 260 picoseconds at 60 K.
• Directly observed coherent electron spin precession under a transverse magnetic field.
• Identified distinct phonon modes (22 meV and 11 meV) influencing spin relaxation and dephasing.

Conclusions:

• Ultrafast hole transfer decouples electron-hole interaction, significantly enhancing spin lifetime.
• Coherent spin precession is realized in 2D perovskites, paving the way for quantum manipulation.
• These materials offer a viable platform for advanced spin-based quantum technologies.