Home > Press > Ultrafast magnetism: heating magnets, freezing time: This study on Gadolinium is completing a series of experiments on Nickel, Iron-Nickel Alloys: The results are useful for developing ultrafast data storage devices
The picture shows the glowing filament which keeps the sample at constant temperatures during the measurements. CREDIT HZB |
Abstract:
New materials should make information processing more efficient, for example, through ultrafast spintronic devices that store data with less energy input. But to date, the microscopic mechanisms of ultrafast demagnetization are not fully understood. Typically, the process of demagnetization is studied by sending an ultrashort laser pulse to the sample, thereby heating it up, and then analyzing how the system evolves in the first picoseconds afterward.
Snapshot of the lattice condition
"Our approach is different," explains Dr. Régis Decker, lead author of the study. "We keep the sample at a certain temperature during the spectra acquisition. And we do that for many temperatures, from -120°C to 450°C for Gd - and much higher (1000°C) for previous experiments with Ni and FeNi. This allows us to quantify the effect of the phonons for each temperature on the ultrafast demagnetization, where the temperatures of the lattice, electrons and spins subsystems evolve with time. In other words, by placing the system at a certain temperature, we do a capture of the lattice condition at a given time after the ultrashort laser pulse and we measure there.”
Gadolinium examined
The element gadolinium has 4f and 5d electron orbitals, which both contribute to its ferromagnetic properties. The higher the temperature, the more the crystalline sample vibrates – and as physicists say: the more the population of phonons increases, and the more likely spin-flips are to occur due to the scattering of electrons with phonons from the crystal lattice.
Scattering rates distinguished
Using the method of inelastic X-ray scattering (RIXS), the physicists were not only able to determine the number of phonons at a given temperature, but also to distinguish the interactions between phonons and 4f- and 5d-electrons. Using the strict X-ray spectroscopic symmetry selection rules, the evaluation succeeded in distinguishing between the scattering rates of the 4f and 5d electrons.
5d electrons interact with phonons
The data show that there is hardly any scattering between the localized 4f electrons and phonons, but most of the scattering process takes place between 5d electrons and phonons, so that a spin-flip only occurs there. "Our approach evidences that the electron-phonon scattering, which is known to be one of the main trigger of ultrafast demagnetization, applies to the 5d electrons only. Interestingly, it also shows the presence of a temperature threshold, which depends on the material, below which this mechanism does not occur. This indicates the existence of another microscopic mechanism at lower temperature, as predicted by theory", Decker explains.
####
For more information, please click here
Contacts:
Antonia Roetger
Helmholtz-Zentrum Berlin für Materialien und Energie
Office: 0049-308-062-43733
Copyright © Helmholtz-Zentrum Berlin für Materialien und Energie
If you have a comment, please Contact us.Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.
Related Links |
Related News Press |
News and information
Simulating magnetization in a Heisenberg quantum spin chain April 5th, 2024
NRL charters Navy’s quantum inertial navigation path to reduce drift April 5th, 2024
Discovery points path to flash-like memory for storing qubits: Rice find could hasten development of nonvolatile quantum memory April 5th, 2024
Magnetism/Magnons
Simulating magnetization in a Heisenberg quantum spin chain April 5th, 2024
Possible Futures
Discovery points path to flash-like memory for storing qubits: Rice find could hasten development of nonvolatile quantum memory April 5th, 2024
With VECSELs towards the quantum internet Fraunhofer: IAF achieves record output power with VECSEL for quantum frequency converters April 5th, 2024
Spintronics
Quantum materials: Electron spin measured for the first time June 9th, 2023
Linearly assembled Ag-Cu nanoclusters: Spin transfer and distance-dependent spin coupling November 4th, 2022
Chip Technology
Discovery points path to flash-like memory for storing qubits: Rice find could hasten development of nonvolatile quantum memory April 5th, 2024
Utilizing palladium for addressing contact issues of buried oxide thin film transistors April 5th, 2024
HKUST researchers develop new integration technique for efficient coupling of III-V and silicon February 16th, 2024
Optical computing/Photonic computing
With VECSELs towards the quantum internet Fraunhofer: IAF achieves record output power with VECSEL for quantum frequency converters April 5th, 2024
Chemical reactions can scramble quantum information as well as black holes April 5th, 2024
Optically trapped quantum droplets of light can bind together to form macroscopic complexes March 8th, 2024
HKUST researchers develop new integration technique for efficient coupling of III-V and silicon February 16th, 2024
Discoveries
Chemical reactions can scramble quantum information as well as black holes April 5th, 2024
New micromaterial releases nanoparticles that selectively destroy cancer cells April 5th, 2024
Utilizing palladium for addressing contact issues of buried oxide thin film transistors April 5th, 2024
Announcements
NRL charters Navy’s quantum inertial navigation path to reduce drift April 5th, 2024
Discovery points path to flash-like memory for storing qubits: Rice find could hasten development of nonvolatile quantum memory April 5th, 2024
Interviews/Book Reviews/Essays/Reports/Podcasts/Journals/White papers/Posters
Simulating magnetization in a Heisenberg quantum spin chain April 5th, 2024
Discovery points path to flash-like memory for storing qubits: Rice find could hasten development of nonvolatile quantum memory April 5th, 2024
Photonics/Optics/Lasers
With VECSELs towards the quantum internet Fraunhofer: IAF achieves record output power with VECSEL for quantum frequency converters April 5th, 2024
Nanoscale CL thermometry with lanthanide-doped heavy-metal oxide in TEM March 8th, 2024
Optically trapped quantum droplets of light can bind together to form macroscopic complexes March 8th, 2024
HKUST researchers develop new integration technique for efficient coupling of III-V and silicon February 16th, 2024
The latest news from around the world, FREE | ||
Premium Products | ||
Only the news you want to read!
Learn More |
||
Full-service, expert consulting
Learn More |
||