Studies of Tailoring of magnetic properties of ultrathin film structures by electromagnetic radiation in a wide spectral range performed in the frame of the project Harmonia 3 (2013-2017) supported by Polish National Science Centre (2012/06/M/ST3/00475). 

The work was done in a broad Polish and international collaboration, using modern experimental techniques, including large-scale facilities. The mostly studied materials were Pt/Co/Pt nanostructures, of the thickness of few tens atomic layers. The samples were produced with molecular beam epitaxy in ultra-high vacuum in Institute of Physics of Polish Academy of Sciences in Warsaw. The main idea of the study was to irradiate the samples with electromagnetic radiation from various sources (with the parameters presented in figure (a)), and to observe irradiation-induced irreversible structural and magnetic modifications.

(a) The used irradiation sources: (1) femtosecond lasers, UwB, Białystok; (2) plasma source EUV, WAT, Warsaw; (3) FLASH, DESY, Hamburg; (4) plasma source CDL, IP ASCR, Prague; (5) excimer laser, HZDR, Rossendorf-Dresden; (6) plasma source PALS, IP ASCR, Prague; (7) Nd:YAG laser (with interference of two beams), University of Konstanz; (8) SACLA X-FEL, SPRring-8, Japan. The green line marks the characteristic cooling time τcool of Pt/Co/Pt system, derived experimentally with the pump-probe technique with the source 1; (b, c) modification of the Pt/Co/Pt system with femtosecond laser pulses from the source 1 (a): optical image (b) and magneto-optical image (c), with the inset of magnetic force microscopy image.

Using all available sources, a possibility of irreversible change of magnetic ordering was observed, from the parallel to perpendicular direction with respect to the sample plane. The effect was observed for all processes disregarding irradiation manner. When the samples were irradiated with ultrashort femtosecond pulses of high enough energy, the metallic films “exploded” resulting in these layers ablation. With longer nanosecond pulses the layers were melting with further recrystallization. An exemplary result of femtosecond pulse-induced modification, done in Białystok, is presented in the figure. The bright spot  in the figure (b) is the area where the metallic films were ablated. In the magneto-optical image (c) of the same region of the sample the white ring denotes the area with the induced out-of-plane magnetization state. The ablated area (from fig. b) is limited by the dashed-line in fig.c. Sub-micrometer magnetic domain structure, recorded using magnetic force microscopy, is shown in insert.

The obtained results can be important in a new branch of studies of ultrafast magnetization processes (such effects are useful in e.g. applications of more dense and faster heat assisted magnetic recording - HAMR), in developing new technologies of production and patterning of magnetic materials, or in applications of magnetic nanostructures as very sensitive detectors of electromagnetic radiation.

Published results:

  1. Maziewski, J.Fassbender, J. Kisielewski, M. Kisielewski, Z. Kurant, P. Mazalski, F. Stobiecki, A. Stupakiewicz, I. Sveklo, M. Tekielak, A. Wawro, and V. Zablotskii, Magnetization states and magnetization processes in nanostructures: From a single layer to multilayers, Phys. Status Solidi A, 211, 1005 (2014).
  2. Kisielewski, W. Dobrogowski, Z. Kurant, A. Stupakiewicz, M. Tekielak, A. Kirilyuk, A. Kimel, Th. Rasing, L. T.Baczewski, A. Wawro, K. Balin, J. Szade, and A. Maziewski, Irreversible modification of magnetic properties of Pt/Co/Pt ultrathin films by femtosecond laser pulses, Journal of Applied Physics 115, 053906 (2014),
  3. Dynowska, J.B. Pelka, D. Klinger, R. Minikayev, A. Bartnik, P. Dluzewski, M. Jakubowski, M. Klepka, A. Petruczik, O.H. Seeck, R. Sobierajski, I. Sveklo, A. A. Wawro and A. Maziewski, Structural investigation of ultrathin Pt/Co/Pt trilayer films under EUV irradiation, Nuclear Instruments and Methods in Physics Research B 364, 33 (2015).
  4. Szerenos, J. Kisielewski, A. Maziewski, and A. Stupakiewicz, “Photoinduced ultrafast magnetization dynamics in yttrium-iron garnet and ultrathin Co films”, IEEE Magn. Lett., 7, 5201404 (2016).
  5. Wojciech Szuszkiewicz, Frédéric Ott, Jan Kisielewski, Iosif Sveklo, Elżbieta Dynowska, Roman Minikayev, Zbigniew Kurant, Rafał Kuna, Marcin Jakubowski, Andrzej Wawro, Ryszard Sobierajski, Andrzej Maziewski. Polarized neutron reflectivity and X-ray scattering measurements as tools to study properties of Pt/Co/Pt ultrathin layers irradiated by femtosecond laser pulses, PHASE TRANSITIONS, 2016, VOL. 89, NO. 4, 328-340, http://dx.doi.org/10.1080/01411594.2016.1156110
  6. Sakamaki, K. Amemiya, I. Sveklo, P. Mazalski, M. O. Liedke, J. Fassbender, Z. Kurant, A. Wawro, and A. Maziewski, Formation of Co nanodisc with enhanced perpendicular magnetic anisotropy driven by Ga+ ion irradiation on Pt/Co/Pt films, PHYSICAL REVIEW B 94, 174422 (2016).
  7. Kisielewski, Z. Kurant, I. Sveklo, M. Tekielak, A. Wawro, and A. Maziewski, Magnetic phases in Pt/Co/Pt films induced by single and multiple femtosecond laser pulses, JOURNAL OF APPLIED PHYSICS, 119, 193901 (2016).
  8. Sveklo, Iosif; Kurant, Zbigniew; Bartnik, Andrzej; Klinger, Dorota; Sobierajski, Ryszard; Wawro, Andrzej; Kisielewski, Jan; Tekielak, Maria; Maziewski, Andrzej, Modification of magnetic properties of Pt/Co/Pt trilayers driven by nanosecond pulses of extreme ultraviolet irradiation, J. Phys. D: Appl. Phys. 50(2017) 025001.
  9. Jan Kisielewski, Iosif Sveklo, Zbigniew Kurant, Andrzej Bartnik, Marcin Jakubowski, Elzbieta Dynowska, Dorota Klinger, Ryszard Sobierajski, Andrzej Wawro, and Andrzej Maziewski, Near infrared and extreme ultraviolet light pulses induced modifications of ultrathin Co films, AIP ADVANCES 7, 056313 (2017).
  10. Kisielewski, Z. Kurant, I. Sveklo, M. Tekielak, E. Dynowska, M. Jakubowski, A. Wawro and A. Maziewski, Modication of magnetization orientation in Pt/Co/Pt ultrathin films by femtosecond laser pulses, IOP Conf. Series: Journal of Physics: Conf. Series 903 (2017) 012020 doi :10.1088/1742-6596/903/1/012020.
  11. Wolska, R. Sobierajski, D. Klinger, M.T. Klepka, I. Jacyna, A. Wawro, M. Jakubowski, J. Kisielewski, Z. Kurant, I. Sveklo, A. Bartnik, A. Maziewski, Polarized XAFS study on the ultrathin Pt/Co/Pt trilayers modified with short light pulses, Nuclear Instruments and Methods in Physics Research B 411 (2017) 112.
  12. Kisielewski, Iosif Sveklo, Zbigniew Kurant, Dmitriy Mitin, Manfred Albrecht, Andrzej Wawro, Andrzej Maziewski i inni, Femtosecond laser pulse-induced perpendicular magnetization in Co ultrathin films with diverse surroundings, IEEE Trans. Magn. 53 (2017) 1100204.
  13. Kisielewski, J. Kisielewski, I. Sveklo, A. Wawro, A. Maziewski, Micromagnetic Simulation of Spatial Distribution of Magnetization in Ultra-Thin Cobalt Layers with Gradient of Magnetic Anisotropy, IEEE Trans. Magn. 53 (2017) 2301204.