Researchers develop method to obtain in-depth and time-resolved view on magnetization

Researchers in Germany, led by the Max Born Institute, have developed a novel technique to obtain “in depth” and time-resolved view on magnetization, employing broadband femtosecond soft X-ray pulses to study the transient evolution of magnetization depth profiles within a magnetic thin film system. This is vital as the future development of functional magnetic devices based on ultrafast optical manipulation of spins requires an understanding of the depth-dependent spin dynamics across the interfaces of complex magnetic heterostructures.

In current information technology, functional magnetic devices typically consist of stacks of thin layers of magnetic and nonmagnetic materials, each only about one nanometer thick. The stacking, choice of atomic species, and the resulting interfaces between the layers are key to the particular function, for example as realized in the giant magnetoresistance read heads in all magnetic hard drives. Over the last years, it was shown that ultrashort laser pulses down to the femtosecond range (1 femtosecond = 10-15 s) can effectively and very fast manipulate the magnetization in a material, allowing a transient change or even permanent reversal of the magnetization state. While these effects have been predominantly studied in simple model systems, future applications will require an understanding of magnetization dynamics in more complex structures with nanometer-scale heterogeneity.