Photocontrol of Exchange Bias Using Cobalt–Iron Prussian Blue Analogues for Applications in Spintronics

Abstract

Multiphysics manipulation of the exchange bias (EB) effect to achieve spin-valve-type spintronic device versatility has begun to attract increasing attention recently. Light-controlled EB is considered to be an attractive approach because the photon mode allows access to a wide variety of materials with high speed, remote control, noncontact, and superior resolution. In this work, we report a detailed photocontrolled EB effect in the well-defined CoO@CoFePBA core–shell heteronanostructure, where the EB effect of this composite can be permanently changed after being exposed to light. As demonstrated, such an interesting photocontrolled effect is actually affected by the composition of the CoFePBA shell. More deeply, the alkali-metal-ion content in the CoFePBA shell is the major factor in controlling these hybrids’ EB effects. Different alkali-metal insertions result in different ratios of the FeIII–CoII magnetic pair to the FeII–CoIII diamagnetic pair in the CoFePBA shell, where FeIII–CoII and FeII–CoIII control the magnetic and photomagnetic effects of CoFePBA, respectively. Therefore, the photocontrolled EB effect of the whole nanohybrid can be adjusted by the amount of alkali-metal insertion in the CoFePBA shell. This study is an advance in the research of light-controlled EB effects, which are useful for the evolution of new functional spintronic devices, such as photomagnetic switches, photomagnetic sensors, and photointelligent information storage materials.