Oxygen doping and polaron magnetic coupling in Alq films
arXiv:2101.07303 · doi:10.1016/j.jmmm.2020.166578
Abstract
The understanding of the Physics underlying the performances of organic spin-valve devices is still incomplete. According to some recent models, spin transport takes place in an impurity band inside the fundamental gap of organic semiconductors. This seems to be confirmed by recent experiments performed with LaSrMnO/Alq/AlO/Co devices. The reported results suggest a possible correlation between the magnetoresistance and the variable oxygen doping in the Alq spacer. In this paper we investigate by means of first-principles calculations the electronic and magnetic properties of O molecules and ions in Alq films to establish whether oxygen plays any important role for spin transport in LaSrMnO/Alq/AlO/Co devices. The conclusion is that it does not. In fact, we show that O molecules do not form an impurity band and there is no magnetic interaction between them. In contrast, we suggest that spin-transport may be enabled by the direct exchange coupling between Alq ions.
arXiv comment6 pages, 2 figures
References in corpus (10)
- Basic obstacle for electrical spin-injection from a ferromagnetic metal into a diffusive semiconductor
- The GW method
- Resolution-of-identity approach to Hartree-Fock, hybrid density functionals, RPA, MP2, and \textit{GW} with numeric atom-centered orbital basis functions
- Self-consistent GW: All-electron implementation with localized basis functions
- Accurate all-electron quasiparticle energies employing the full-potential augmented planewave method
- Oxygen stoichiometry and instability in aluminium oxide tunnel barrier layers
- Hanle effect missing in a prototypical organic spintronic device
- Vertical organic spin valves in perpendicular magnetic fields
- Charge-induced spin polarization in non-magnetic organic molecule Alq
- Controlling magnetoresistance by oxygen impurities in Mq3-based molecular spin valves