Dynamic spin polarization in organic semiconductors with intermolecular exchange interaction

Abstract

It is shown that in organic semiconductors where organic magnetoresistance (OMAR) is observed, the exchange interaction between electrons and holes localized at different molecules leads to dynamic spin polarization in the direction of the applied magnetic field. The polarization appears even at room temperature due to the non-equilibrium conditions. The strong spin polarization requires exchange energy to be comparable with Zeeman energy in the external field and be larger or comparable with the energy of hyperfine interaction of electron and nuclear spins. The exchange interaction also modifies the lineshape of OMAR.

References in corpus (11)

• Basic obstacle for electrical spin-injection from a ferromagnetic metal into a diffusive semiconductor
• Large magnetoresistance in $\pi$-conjugated semiconductor thin film devices
• Spin relaxation in a nanowire organic spin valve: Observation of extremely long spin relaxation times
• Vertical organic spin valves in perpendicular magnetic fields
• Dynamic polarization of electron spins interacting with nuclei in semiconductor nanostructures
• Magnetoresistance in organic semiconductors: including pair correlations in the kinetic equations for hopping transport
• Dynamic polarization of electron spins in indirect band gap (In,Al)As/AlAs quantum dots in weak magnetic field: experiment and theory
• Microscopic theory of OMAR based on kinetic equations for quantum spin correlations
• The system of correlation kinetic equations and the generalized equivalent circuit for hopping transport
• Image of dynamic local exchange interactions in the dc magnetoresistance of spin-polarized current through a dopant
• Oxygen doping and polaron magnetic coupling in Alq${}_3$ films