Enhancing all-optical switching of magnetization by He ion irradiation

All-optical switching (AOS) of magnetization by a single femtosecond laser pulse in Co/Gd based synthetic ferrimagnets is the fastest magnetization switching process. On the other hand, He ion irradiation has become a promising tool for interface engineering of spintronic material platforms, giving rise to significant modification of magnetic properties. In this paper, we explore the use of He ion irradiation to enhance single pulse AOS of Co/Gd bilayer-based synthetic ferrimagnets. The intermixing of the constituent magnetic layers by He ion irradiation was both numerically simulated and experimentally verified. We theoretically modeled the effects of intermixing on AOS using the layered microscopic 3-temperature model and found that AOS is enhanced significantly by breaking the pristine Co/Gd interface through intermixing. Following this notion, we studied the threshold fluence of AOS as a function of He ion irradiation fluence. We found that the AOS threshold fluence can be reduced by almost 30%. Our study reveals the control of AOS by He ion irradiation, which opens up an industrially compatible approach for local AOS engineering.

This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie Grant Agreement Nos. 860060 and 861300. This project is also part of the research programme financed by the Netherlands Organisation for Scientific Research (NWO). Solliance and the Dutch province of Noord-Brabant are acknowledged for funding the TEM facility.