Photovoltaic Control of Ferromagnetism for Flexible Spintronics.

The demand for low-power flexible spintronics for sensing, communicating, and data processing applications boosts an intense search for novel ways of controlling magnetism. In this work, a photovoltaic controllable flexible spintronic device within a Kapton/Ta/Co/(PC71BM/PTB7-Th)/Pt heterostructure was demonstrated, and the magnetic anisotropy change of this flexible heterostructure as a function of the external light radiation and strain was quantitatively determined. 150 mW/cm2 white light illumination induced 489 Oe out-of-plane ferromagnetic resonance field modulation, which was attributed to the photogenerated electron doping in the cobalt film. The chemical contamination effect and the interfacial oxidation effect during the photovoltaic doping process were eliminated. Moreover, it was found that the working function of the thin-film electrodes were different from the bulk values via an ultraviolet photoelectron spectroscopy test. Our results on flexible photovoltaic spintronics systems will invigorate the research toward the development of solar-driven energy-efficient spintronics.