English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Magnetic phenomena are ubiquitous in our surroundings and indispensable formodern science and technology, but it is notoriously difficult to change themagnetic order of a material in a rapid way. However, if a thin nickel film issubjected to ultrashort laser pulses, it can lose its magnetic order almostcompletely within merely femtosecond times. This phenomenon, in the meantimealso observed in many other materials, has connected magnetism with femtosecondoptics in an efficient, ultrafast and complex way, offering opportunities forrapid information processing or ultrafast spintronics at frequenciesapproaching those of light. Consequently, the physics of ultrafastdemagnetization is central to modern material research, but a crucial questionhas remained elusive: If a material loses its magnetization within onlyfemtoseconds, where is the missing angular momentum in such short time? Here weuse ultrafast electron diffraction to reveal in nickel an almost instantaneous,long-lasting, non-equilibrium population of anisotropic high-frequency phononsthat appear as quickly as the magnetic order is lost. The anisotropy plane isperpendicular to the direction of the initial magnetization and the atomicoscillation amplitude is 2 pm. We explain these observations by means ofcircularly polarized phonons that quickly absorb the missing angular momentumof the spin system before the slower onset of a macroscopic sample rotation.The time that is needed for demagnetization is related to the time it takes toaccelerate the atoms. These results provide an atomistic picture of ultrafastdemagnetization under adherence to all conservation laws but also demonstratethe general importance of polarized phonons for non-equilibrium dynamics andprovide innovative ways for controlling materials on atomic dimensions.

Polarized phonons carry the missing angular momentum in femtosecond demagnetization