Summation of flux pinning by columnar defects tilted at different angles in YBCO thin films

Sueyoshi, Tetsuro*; Enokihata, Ryusei*; Yamaguchi, Hiroshi*; Fujiyoshi, Takanori*; Okuno, Yasuki*; Ishikawa, Norito

IEEE Transactions on Applied Superconductivity, 31(5), p.8000305_1 - 8000305_5, 2021/08

https://ieeexplore.ieee.org/document/9356111

Angular behaviors of critical current density Jc at 77 K, 1 T were investigated in YBCO films with columnar defects (CDs) tilted at small angles to the ab-plane before and after the additional introduction of CDs at different angles, where CDs were installed by heavy-ion irradiations. The enhanced Jc at by the initial irradiation at i=85 relative to the c-axis was reduced by the additional irradiation at i=75, whereas the Jc was increased at the intermediate angle between the two irradiation angles. The addition of CDs at i=0 also lowered the Jc around , which were enhanced by the initial irradiation angles of i=80.

Origin of magnetovolume effect in a cobaltite

Miao, P.*; Tan, Z.*; Lee, S. H.*; Ishikawa, Yoshihisa*; Torii, Shuki*; Yonemura, Masao*; Koda, Akihiro*; Komatsu, Kazuki*; Machida, Shinichi*; Sano, Asami; et al.

Physical Review B, 103(9), p.094302_1 - 094302_18, 2021/03

https://doi.org/10.1103/PhysRevB.103.094302

The layered perovskite PrBaCoO demonstrates a strong negative thermal expansion (NTE) which holds potential for being fabricated into composites with zero thermal expansion. The NTE was found to be intimately associated with the spontaneous magnetic ordering, known as magneto-volume effect (MVE). Here we report with compelling evidences that the continuous-like MVE in PrBaCoO is intrinsically of discontinuous character, originating from an magnetoelectric transition from an antiferromagnetic insulating large-volume (AFILV) phase to a ferromagnetic less-insulating small-volume (FLISV) phase. Furthermore, the magnetoelectric effect (ME) shows high sensitivity to multiple external stimuli such as temperature, carrier doping, hydrostatic pressure, magnetic field etc. In contrast to the well-known ME such as colossal magnetoresistance and multi-ferroic effect which involve symmetry breaking of crystal structure, the ME in the cobaltite is purely isostructural. Our discovery provides a new path way to realizing the ME as well as the NTE, which may find applications in new techniques.

Flux pinning by columnar defects along -axis in -axis oriented YBCO thin films

Sueyoshi, Tetsuro*; Iwanaga, Yasuya*; Fujiyoshi, Takanori*; Takai, Yosuke*; Muta, Mitsuhiro*; Mukaida, Masashi*; Ichinose, Ataru*; Ishikawa, Norito

IEEE Transactions on Applied Superconductivity, 29(5), p.8003204_1 - 8003204_4, 2019/08

https://doi.org/10.1109/TASC.2019.2896473

Columnar defects (CDs) along -axis were installed into an in-plane aligned -axis-oriented YBaCuO film by using heavy-ion irradiation, in order to clarify the influence of CDs on flux pinning properties around B. The critical current density at B significantly decreases after the irradiation, since the CDs act as a channel for flux creep along their length. The magnetic field dependence of at B, on the other hand, is weakened by the introduction of CDs.

Materials and Life Science Experimental Facility (MLF) at the Japan Proton Accelerator Research Complex, 2; Neutron scattering instruments

Nakajima, Kenji; Kawakita, Yukinobu; Ito, Shinichi*; Abe, Jun*; Aizawa, Kazuya; Aoki, Hiroyuki; Endo, Hitoshi*; Fujita, Masaki*; Funakoshi, Kenichi*; Gong, W.*; et al.

Quantum Beam Science (Internet), 1(3), p.9_1 - 9_59, 2017/12

https://doi.org/10.3390/qubs1030009

The neutron instruments suite, installed at the spallation neutron source of the Materials and Life Science Experimental Facility (MLF) at the Japan Proton Accelerator Research Complex (J-PARC), is reviewed. MLF has 23 neutron beam ports and 21 instruments are in operation for user programs or are under commissioning. A unique and challenging instrumental suite in MLF has been realized via combination of a high-performance neutron source, optimized for neutron scattering, and unique instruments using cutting-edge technologies. All instruments are/will serve in world-leading investigations in a broad range of fields, from fundamental physics to industrial applications. In this review, overviews, characteristic features, and typical applications of the individual instruments are mentioned.

Flux pinning properties in YBCO films with growth-controlled nano-dots and heavy-ion irradiation defects

Sueyoshi, Tetsuro*; Kotaki, Tetsuya*; Uraguchi, Yusei*; Suenaga, Momotaro*; Makihara, Takahiro*; Fujiyoshi, Takanori*; Ishikawa, Norito

Physica C, 530, p.72 - 75, 2016/11

https://doi.org/10.1016/j.physc.2016.04.011

In order to clarify the influence of size and spatial distribution of three-dimensional pinning centers (3D-PCs) on hybrid flux pinning, columnar defects (CDs) were installed by using 200 MeV Xe ions along the -axis direction into quasi-multilayered films consisting of YBaCuOy layers and pseudo layers of BaSnO. The positive effect of the BaSnO doping on the hybrid flux pinning stands out for the critical current density around in high magnetic field and/or inclined magnetic field off the -axis, whereas there is little difference in the at among the same growth temperature samples for low magnetic field. In the case of the in-plane distributed BaSnO nano-dots, the Jc around is remarkably enhanced, whereas there is a detrimental effect on the Jc around . These imply that the tuning of 3D-PCs is one of the keys to improve the at all magnetic field orientations for the hybrid flux pinning.

Angular behaviour of critical current density in YBaCuOy thin films with crossed columnar defects

Sueyoshi, Tetsuro*; Sogo, Takehiro*; Nishimura, Takahiro*; Fujiyoshi, Takanori*; Mitsugi, Fumiaki*; Ikegami, Tomoaki*; Awaji, Satoshi*; Watanabe, Kazuo*; Ichinose, Ataru*; Ishikawa, Norito

Superconductor Science and Technology, 29(6), p.065023_1 - 065023_8, 2016/05

https://doi.org/10.1088/0953-2048/29/6/065023

Columnar defects (CDs) were installed into YBaCuOy thin films at the crossing angle relative to the c-axis using 200 MeV Xe ions. The width of a Jc peak occurring around B//c linearly increases with broadening the CD-crossing angle, where its shape maintains a single peak in the small angle range. The CDs crossing at 45, on the other hand, drastically change the angular behaviour of Jc around B//c, the Jc is equally elevated over the angular region from -45 to +45 in lower magnetic field, whereas the rapid reduction of the Jc around B//c occurs with increasing the magnetic field, leading to the appearance of double peaks at the irradiation angles, -45 and +45.

Influence of discontinuous columnar defects on flux pinning properties in GdBCO coated conductors

Sueyoshi, Tetsuro*; Kotaki, Tetsuya*; Furuki, Yuichi*; Uraguchi, Yusei*; Kai, Takashi*; Fujiyoshi, Takanori*; Shimada, Yusuke*; Yasuda, Kazuhiro*; Ishikawa, Norito

IEEE Transactions on Applied Superconductivity, 25(3), p.6603004_1 - 6603004_4, 2015/06

https://doi.org/10.1109/TASC.2014.2374554

To investigate the effect of discontinuity of 1-D pinning centers on the flux pinning in a wide range of magnetic field directions, discontinuous columnar defects (CDs) and continuous CDs were formed in GdBCO coated conductors using Xe-ion irradiations with 80 and 270 MeV, respectively. An overall shift upward in Jc, for the 80-MeV-irradiated sample compared to the 270-MeV-irradiated one, can be observed in every direction of magnetic field, which is more remarkable as temperature decreases. This implies a synergetic effect of the pinning interaction between the linearity and the discontinuity for the discontinuous CDs.

Influence of anisotropically splayed columnar defects on the angular dependence of critical current density in YBCO thin films

Sueyoshi, Tetsuro*; Furuki, Yuichi*; Fujiyoshi, Takanori*; Mitsugi, Fumiaki*; Ikegami, Tomoaki*; Ishikawa, Norito

Teion Kogaku, 49(3), p.139 - 144, 2014/03

https://doi.org/10.2221/jcsj.49.139

Columnar defects (CDs) produced by heavy-ion irradiations in high-Tc superconductors such as YBaCuOy (YBCO) are the most effective pinning centers to immobilize flux lines, leading to the enhancement of critical current density Jc. In addition, slight dispersion (splay) in directions of CDs can further improve the Jc. In this work, YBCO thin films were irradiated using 200 MeV Xe ions at two angles relative to the c-axis in two geometries where the direction of current is perpendicular (mode A) or parallel to the splay plane (mode B), to investigate the influence of the direction of splay plane on the flux pinning properties.

Research and development of radiation measuring instruments for lake,pond and river sediments, 1

Yanagizawa, Koichi; Hayashi, Toshio*; Oinuma, Masaru*; Takemori, Makoto*; Ishikawa, Takanori*; Okaya, Tomoichi*; Nishigaki, Makoto*

Shadan Hojin Butsuri Tansa Gakkai Dai-129-Kai (Heisei-25-Nendo Shuki) Gakujutsu Koenkai Koen Rombunshu, p.287 - 288, 2013/10

The development of instrument aimed at the measurement of radiation dose in the sediment of lakes, rivers and sea bed been carried out. The radiation level contained in the sediment at the bottom of lake and so on is anticipated to indicate the existence of locally high radiation spots where the diffused radioactive substance is accumulated in ponds, rivers and lakes by rainwater. The radiation dose measurement system this time is to measure -ray by dragging the detector, which is called probe, at the bottom of lakes to understand the radiation dose over wide areas. Furthermore, the measurement of resistivity value at the bottom of lakes is simultaneously dose to presume the condition of sediment.

Probabilistic safety assessment on experimental fast reactor Joyo; Level1 PSA for internal events

Ishikawa, Koki; Takamatsu, Misao; Kawahara, Hirotaka; Mihara, Takatsugu; Kurisaka, Kenichi; Terano, Toshihiro; Murakami, Takanori; Noritsugi, Akihiro; Iseki, Atsushi; Saito, Takakazu; et al.

JAEA-Technology 2009-004, 140 Pages, 2009/05

JAEA-Technology-2009-004.pdf:2.0MB

Probabilistic safety assessment (PSA) has been applied to nuclear plants as a method to achieve effective safety regulation and safety management. In order to establish the PSA standard for fast breeder reactor (FBR), the FBR-PSA for internal events in rated power operation is studied by Japan Atomic Energy Agency (JAEA). The level1 PSA on the experimental fast reactor Joyo was conducted to investigate core damage probability for internal events with taking human factors effect and dependent failures into account. The result of this study shows that the core damage probability of Joyo is 5.010 per reactor year (/ry) and that the core damage probability is smaller than the safety goal for existed plants (10 ry) and future plants (10/ry) in the IAEA INSAG-12 (International Nuclear Safety Advisory Group) basic safety principle.