Magnetic Switching in Granular FePt Layers Promoted by Near-Field Laser Enhancement

Patrick W. Granitzka; Emmanuelle Jal; Loïc Le Guyader; Matteo Savoini; Daniel J. Higley; Tianmin Liu; Zhao Chen; Tyler Chase; Hendrik Ohldag; Georgi L. Dakovski; William F. Schlotter; Sebastian Carron; Matthias C. Hoffman; Alexander X. Gray; Padraic Shafer; Elke Arenholz; Olav Hellwig; Virat Mehta; Yukiko K. Takahashi; Jian Wang; Eric E. Fullerton; Joachim Stöhr; Alexander H. Reid; Hermann A. Dürr

doi:10.1021/acs.nanolett.7b00052

Magnetic Switching in Granular FePt Layers Promoted by Near-Field Laser Enhancement

Patrick W. Granitzka, Emmanuelle Jal^*, Loïc Le Guyader, Matteo Savoini, Daniel J. Higley, Tianmin Liu, Zhao Chen, Tyler Chase, Hendrik Ohldag, Georgi L. Dakovski, William F. Schlotter, Sebastian Carron, Matthias C. Hoffman, Alexander X. Gray, Padraic Shafer, Elke Arenholz, Olav Hellwig, Virat Mehta, Yukiko K. Takahashi, Jian WangEric E. Fullerton, Joachim Stöhr, Alexander H. Reid, Hermann A. Dürr

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

20 Citations (Scopus)

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.

Original language	English
Pages (from-to)	2426-2432
Number of pages	7
Journal	Nano Letters
Volume	17
Issue number	4
DOIs	https://doi.org/10.1021/acs.nanolett.7b00052
Publication status	Published - 2017 Apr 12
Externally published	Yes

Keywords

FePt
X-ray scattering
magnetic switching
pump-probe
ultrafast magnetism

ASJC Scopus subject areas

Bioengineering
Chemistry(all)
Materials Science(all)
Condensed Matter Physics
Mechanical Engineering

Access to Document

10.1021/acs.nanolett.7b00052

Cite this

Granitzka, P. W., Jal, E., Le Guyader, L., Savoini, M., Higley, D. J., Liu, T., Chen, Z., Chase, T., Ohldag, H., Dakovski, G. L., Schlotter, W. F., Carron, S., Hoffman, M. C., Gray, A. X., Shafer, P., Arenholz, E., Hellwig, O., Mehta, V., Takahashi, Y. K., ... Dürr, H. A. (2017). Magnetic Switching in Granular FePt Layers Promoted by Near-Field Laser Enhancement. Nano Letters, 17(4), 2426-2432. https://doi.org/10.1021/acs.nanolett.7b00052

Granitzka, PW, Jal, E, Le Guyader, L, Savoini, M, Higley, DJ, Liu, T, Chen, Z, Chase, T, Ohldag, H, Dakovski, GL, Schlotter, WF, Carron, S, Hoffman, MC, Gray, AX, Shafer, P, Arenholz, E, Hellwig, O, Mehta, V, Takahashi, YK, Wang, J, Fullerton, EE, Stöhr, J, Reid, AH & Dürr, HA 2017, 'Magnetic Switching in Granular FePt Layers Promoted by Near-Field Laser Enhancement', Nano Letters, vol. 17, no. 4, pp. 2426-2432. https://doi.org/10.1021/acs.nanolett.7b00052

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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",

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doi = "10.1021/acs.nanolett.7b00052",

language = "English",

volume = "17",

pages = "2426--2432",

journal = "Nano Letters",

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T1 - Magnetic Switching in Granular FePt Layers Promoted by Near-Field Laser Enhancement

AU - Granitzka, Patrick W.

AU - Jal, Emmanuelle

AU - Le Guyader, Loïc

AU - Savoini, Matteo

AU - Higley, Daniel J.

AU - Liu, Tianmin

AU - Chen, Zhao

AU - Chase, Tyler

AU - Ohldag, Hendrik

AU - Dakovski, Georgi L.

AU - Schlotter, William F.

AU - Carron, Sebastian

AU - Hoffman, Matthias C.

AU - Gray, Alexander X.

AU - Shafer, Padraic

AU - Arenholz, Elke

AU - Hellwig, Olav

AU - Mehta, Virat

AU - Takahashi, Yukiko K.

AU - Wang, Jian

AU - Fullerton, Eric E.

AU - Stöhr, Joachim

AU - Reid, Alexander H.

AU - Dürr, Hermann A.

N1 - 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: © 2017 American Chemical Society.

PY - 2017/4/12

Y1 - 2017/4/12

N2 - 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.

AB - 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.

KW - FePt

KW - X-ray scattering

KW - magnetic switching

KW - pump-probe

KW - ultrafast magnetism

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U2 - 10.1021/acs.nanolett.7b00052

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JO - Nano Letters

JF - Nano Letters

IS - 4

ER -

Magnetic Switching in Granular FePt Layers Promoted by Near-Field Laser Enhancement

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Keywords

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