Magnetization reversal of ferromagnetic nanoparticles induced by a stream of polarized electrons

• Ferromagnetic nanoparticle in STM with ferromagnetic tip.
• Change of the direction of nanoparticle magnetization by current I>Icr=9 nA.
• GMR effect used to control change of magnetization.

The remagnetization of ferromagnetic Fe3O4 nanoparticles of several thousand cubic nanometers by spin-polarized current is investigated. For this purpose, magnetite nanoparticles are synthesized and deposited on a conductive nonmagnetic substrate. The remagnetization is conducted in high-vacuum scanning tunneling microscope (STM). The STM tip from magnetized iron wire constitutes one electrode while the ferromagnetic nanoparticle on the graphite surface represents the second electrode. The measured threshold value of remagnetization current (Ithresh=9 nA) is the lowest value of current at which remagnetization occurs. The change in nanoparticle magnetization is detected by the effect of giant magnetic resistance, specifically, the dependence of the weak polarized current (I