Spintronic Pathways in a Nonconjugated Radical Polymer Glass

Area of Science:

• Materials Science
• Polymer Chemistry
• Spintronics

Background:

• Radical chemistries are gaining attention for applications in organic electronics, optoelectronics, and magneto-responsive systems.
• The spin-transport capabilities of magnetically active glassy polymers have remained largely unexplored.

Purpose of the Study:

• To investigate the spin-transport characteristics of the radical polymer poly(4-glycidyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl) (PTEO).
• To demonstrate sustained spin-selective currents and analyze magnetoresistance effects in PTEO-based devices.

Main Methods:

• Incorporation of PTEO into device geometries with magnetically polarized electrodes.
• Annealing of PTEO thin films above their glass transition temperature.
• Ferromagnetic resonance spin-pumping measurements at the NiFe/PTEO interface.

Main Results:

• PTEO enables sustained spin-selective currents.
• A giant magnetoresistance (MR) effect of approximately 80% was observed at 4 K after annealing.
• A large effective spin-mixing conductance of 1.18 × 10^19 m^-2 was measured at the NiFe/PTEO interface.
• Effective propagation of pure spin currents through PTEO with a spin diffusion length of 90.4 nm was achieved in NiFe/PTEO/Pd multilayer devices.

Conclusions:

• This work presents the first demonstration of spin transport in a nonconjugated radical polymer.
• PTEO exhibits promising spin-transporting potential, with performance comparable to conventional doped conjugated polymers and surpassing inorganic/metallic systems.
• The findings underscore the potential of radical polymers for advanced spintronic applications.