Magnetic switching in granular FePt layers promoted by near-field laser enhancement
- SLAC National Accelerator Lab., Menlo Park, CA (United States); Univ. of Amsterdam, Amsterdam (The Netherlands)
- SLAC National Accelerator Lab., Menlo Park, CA (United States); Sorbone Univ., Paris (France)
- SLAC National Accelerator Lab., Menlo Park, CA (United States); European XFEL GmbH, Schenefeld (Germany)
- Eidgenossische Technische Hochschule (ETH) Zurich, Zurich (Switzerland)
- SLAC National Accelerator Lab., Menlo Park, CA (United States); Stanford Univ., Stanford, CA (United States)
- SLAC National Accelerator Lab., Menlo Park, CA (United States)
- SLAC National Accelerator Lab., Menlo Park, CA (United States); California Lutheran Univ., Thousand Oaks, CA (United States)
- Temple Univ., Philadelphia, PA (United States)
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- HGST a Western Digital Co., San Jose, CA (United States); Chemnitz Univ. of Technology (Germany). Inst. of Physics; Helmholtz-Zentrum Dresden–Rossendorf (HZDR), Dresden (Germany). Inst. of Ion Beam Physics and Materials Research
- HGST a Western Digital Co., San Jose, CA (United States); Thomas J. Watson Research Center, Yorktown Heights, NY (United States)
- National Institute for Materials Science, Tsukuba (Japan)
- Univ. of California San Diego, La Jolla, CA (United States)
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.
- Research Organization:
- SLAC National Accelerator Laboratory (SLAC), Menlo Park, CA (United States); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences & Engineering Division; US Department of the Navy, Office of Naval Research (ONR)
- Grant/Contract Number:
- AC02-05CH11231; AC02-76SF00515
- OSTI ID:
- 1361059
- Alternate ID(s):
- OSTI ID: 1458492
- Journal Information:
- Nano Letters, Vol. 17, Issue 4; ISSN 1530-6984
- Publisher:
- American Chemical SocietyCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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