SCIENTIFIC ACHIEVEMENT
At the Advanced Light Source (ALS), striped patterns of spins in a magnetic thin film were found to evolve under an applied magnetic field in steps reminiscent of a structure known as the “Devil’s Staircase.”
SIGNIFICANCE AND IMPACT
Such studies are valuable for understanding competing interactions at the atomic level for applications such as magnetic sensors and spintronic devices.
Devilishly complex systems
The “Devil’s Staircase” is a peculiar mathematical function that rises continuously but has no slope (i.e., its derivative is zero almost everywhere). This is because it consists of “runs” (flat sections) connected by “rises” that are fractal: each contains successively smaller copies of the main step, to the infinitesimal limit. Similar structures have emerged in phenomena ranging from earthquakes to charge density waves—systems characterized by competing pressures that result in periods of stability punctuated by short bursts of activity.
Here, researchers report the observation of novel staircase patterns in the evolution of spin-stripe domains in an iron/gadolinium (Fe/Gd) multilayer system. Theoretical modeling that builds on the measurements revealed which of the competing atomic-level interactions in this system is the dominant cause of the staircase structure. The findings help unravel the complex interplay of forces affecting spins in systems relevant to applications in magnetic sensing, information storage, and spintronics.
Read more on the ALS website
Image: A scattering image of one of the sample’s magnetic phases