Colloquium: Ultra-fast all optical switching in spintronic devices

We investigate magnetization reversal driven by the direct interaction between ultrashort laser pulses and magnetic order. Beyond this direct interaction, we also explore how femtosecond laser excitation can generate transient heat spikes or spin-polarized current pulses, which in turn can be harnessed to reverse magnetization in thin ferromagnetic films and magnetic heterostructures [1–3]. A particular focus is placed on deterministic switching induced by single femtosecond or picosecond laser pulses in spintronic devices such as spin valves [4–9] and magnetic tunnel junctions [12]. We demonstrate ultrafast magnetization reversal—initiated in less than one picosecond—in various ferrimagnetic and ferromagnetic spin-valve architectures, including both perpendicularly magnetized [4–9] and in-plane magnetized [10-11] configurations. Notably, in rare-earth-free spin valves of the form [Pt/Co]/Cu/[Co/Pt], the free magnetic layer can be switched from both a parallel to antiparallel alignment and an antiparallel to a parallel alignment, indicating the presence of an intense and ultrafast source of angular momentum transfer. Such effect as also been observed in Magnetic tunnel junction[12]. Furthermore, in exchange-biased IrMn/GdCo bilayers, a single laser pulse not only reverses the ferrimagnetic GdCo layer but also alters the sign of the exchange bias, revealing that the magnetic state of the antiferromagnetic IrMn layer is also modified by optical excitation [13]. Altogether, these results highlight the potential of combining spintronic architectures with ultrafast optical control for next-generation magnetic switching technologies.

 

 

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