Sunlight-induced tri-state spin memory in photovoltaic/ferromagnetic heterostructure

Abstract

The advanced spintronic devices demand a new routine of manipulating spin states effectively with low power consumption, fast switching, and non-volatility. Here, a photovoltaic heterojunction structure of (Cu, Ta)/Co40Fe40B20/(Ta, Cu) on a p-n junction Si wafer is proposed. The saturation magnetizations (Ms) tunability under sunlight illumination is decreased by ∼5–8 %. The first principle calculations reveal that the insert Cu or Ta layer promoted the photoelectron transmission, leading to a larger Ms tunability. Moreover, the Ta layer also generates a barrier between the p-n junction and CoFeB to keep the photoelectrons in the CoFeB layer, creating a non-volatility and sunlight/electrical dual-regulated tri-state magnetization change. Element-resolved X-ray magnetic circular dichroism (XMCD) measurement is also performed to determine the diminished intrinsic magnetism and corresponding non-volatility during sunlight illumination. These fundings explore a new method of magnetic modulation further to expand the non-volatile, low-power sunlight-driven spintronics.