@article{825cebba48f74fd3b048101e8cd2eb04,
title = "Magnetic Switching in Granular FePt Layers Promoted by Near-Field Laser Enhancement",
abstract = "Light-matter interaction at the nanoscale in magnetic materials is a topic of intense research in view of potential applications in next-generation high-density magnetic recording. Laser-assisted switching provides a pathway for overcoming the material constraints of high-anisotropy and high-packing density media, though much about the dynamics of the switching process remains unexplored. We use ultrafast small-angle X-ray scattering at an X-ray free-electron laser to probe the magnetic switching dynamics of FePt nanoparticles embedded in a carbon matrix following excitation by an optical femtosecond laser pulse. We observe that the combination of laser excitation and applied static magnetic field, 1 order of magnitude smaller than the coercive field, can overcome the magnetic anisotropy barrier between {"}up{"} and {"}down{"} magnetization, enabling magnetization switching. This magnetic switching is found to be inhomogeneous throughout the material with some individual FePt nanoparticles neither switching nor demagnetizing. The origin of this behavior is identified as the near-field modification of the incident laser radiation around FePt nanoparticles. The fraction of not-switching nanoparticles is influenced by the heat flow between FePt and a heat-sink layer.",
keywords = "FePt, X-ray scattering, magnetic switching, pump-probe, ultrafast magnetism",
author = "Granitzka, {Patrick W.} and Emmanuelle Jal and {Le Guyader}, Lo{\"i}c and Matteo Savoini and Higley, {Daniel J.} and Tianmin Liu and Zhao Chen and Tyler Chase and Hendrik Ohldag and Dakovski, {Georgi L.} and Schlotter, {William F.} and Sebastian Carron and Hoffman, {Matthias C.} and Gray, {Alexander X.} and Padraic Shafer and Elke Arenholz and Olav Hellwig and Virat Mehta and Takahashi, {Yukiko K.} and Jian Wang and Fullerton, {Eric E.} and Joachim St{\"o}hr and Reid, {Alexander H.} and D{\"u}rr, {Hermann A.}",
note = "Funding Information: Work at SIMES is supported by the Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division, under Contract No. DE-AC02-76SF00515. Work at UCSD is supported by the Office of Naval Research MURI program. Use of the Linac Coherent Light Source, SLAC National Accelerator Laboratory, is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences under Contract No. DE-AC02-76SF00515. Work at the Advanced Light Source is supported by the Director, Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. Publisher Copyright: {\textcopyright} 2017 American Chemical Society.",
year = "2017",
month = apr,
day = "12",
doi = "10.1021/acs.nanolett.7b00052",
language = "English",
volume = "17",
pages = "2426--2432",
journal = "Nano Letters",
issn = "1530-6984",
publisher = "American Chemical Society",
number = "4",
}