Structure and magnetic properties of Fe nanoparticles in amorphous silica implanted with Fe ions and effect of subsequent energetic heavy ion irradiation

Iwase, Akihiro*; Fukuda, Kengo*; Saito, Yuichi*; Okamoto, Yoshihiro; Semboshi, Satoshi*; Amekura, Hiroshi*; Matsui, Toshiyuki*

Journal of Applied Physics, 132(16), p.163902_1 - 163902_10, 2022/10

https://doi.org/10.1063/5.0102438

Amorphous SiO samples were implanted with 380 keV Fe ions at room temperature. After implantation, some of the samples were irradiated with 16 MeV Au ions. magnetic properties were investigated using a SQUID magnetometer, and the morphology of the Fe-implanted SiO samples was examined using transmission electron microscopy and X-ray absorption spectroscopy (EXAFS and XANES), which showed that the size of Fe nanoparticles was increasing The size of Fe nanoparticles increased with increasing Fe implantation amount; some of the Fe nanoparticles consisted of Fe oxides, and the valence and structure of Fe atoms became closer to that of metallic -Fe with increasing Fe injection amount. The magnetization-field curve of the sample implanted with a small amount of Fe was reproduced by Langevin's equation, suggesting that the Fe nanoparticles behave in a superparamagnetic manner. In addition, when a large amount of Fe was implanted, the magnetization-magnetic field curve shows a ferromagnetic state. These magnetic property results are consistent with the X-ray absorption results. Subsequent 16 MeV Au irradiation crushed the Fe nanoparticles, resulting in a decrease in magnetization.

Simulation and experiments of the laser induced breakdown of air for femtosecond to nanosecond order pulses

Koga, J. K.; Moribayashi, Kengo; Fukuda, Yuji; Bulanov, S. V.; Sagisaka, Akito; Ogura, Koichi; Daido, Hiroyuki; Yamagiwa, Mitsuru; Kimura, Toyoaki*; Fujikawa, Taketoshi*; et al.

Journal of Physics D; Applied Physics, 43(2), p.025204_1 - 025204_15, 2010/01

https://doi.org/10.1088/0022-3727/43/2/025204

Simulation and experiments of the laser induced breakdown of air for femtosecond to picosecond order pulses

Koga, J. K.; Moribayashi, Kengo; Fukuda, Yuji; Bulanov, S. V.; Sagisaka, Akito; Ogura, Koichi; Daido, Hiroyuki; Yamagiwa, Mitsuru; Kimura, Toyoaki; Fujikawa, Taketoshi*; et al.

no journal, , 

Interactions of clusters with X-ray free electron laser

Fukuda, Yuji; Nakamura, Tatsufumi; Moribayashi, Kengo; Kishimoto, Yasuaki*

no journal, , 

In order to investigate the damage of a single bio-molecule when it is irradiated by a strong X-ray free electron laser (XFEL) pulse, time evolution of a single carbon cluster with diameter of 30 nm irradiated with 10-fs XFEL pulse is studied by using particle-in-cell (PIC) code including field-ionization and collisional ionization. The cluster is ionized up to C within a femtosecond from the surface by strong sheath fields (TV/m). Then, the cluster is gradually ionized to higher charge states by collisional ionization. Target size and XFEL pulse intensity have an effect on ionization processes due to the change of sheath field intensity. This result indicates that the field ionization by strong sheath field plays an important role to the damage of a single bio-molecule.

The Polarized field and internal structure of a cluster irradiated by laser pulse

Nishiyama, Hiroshi*; Masaki, Tomohiro*; Fukuda, Yuji; Moribayashi, Kengo; Kishimoto, Yasuaki*

no journal, , 

no abstracts in English

Theory and Computer simulation for determining 3D structures of biomolecules by XFEL

Kono, Hidetoshi; Go, Nobuhiro*; Moribayashi, Kengo; Fukuda, Yuji

no journal, , 

no abstracts in English

Blue-shifting of high power laser pulses and the relation to breakdown

Koga, J. K.; Moribayashi, Kengo; Fukuda, Yuji; Bulanov, S. V.; Sagisaka, Akito; Ogura, Koichi; Daido, Hiroyuki; Yamagiwa, Mitsuru

no journal, ,