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Journal Articles

Effects of particle irradiations on vortex states in iron-based superconductors

Tamegai, Tsuyoshi*; Taen, Toshihiro*; Yagyuda, Hidenori*; Tsuchiya, Yuji*; Mohan, S.*; Taniguchi, Tomotaka*; Nakajima, Yasuyuki*; Okayasu, Satoru; Sasase, Masato*; Kitamura, Hisashi*; et al.

Superconductor Science and Technology, 25(8), p.084008_1 - 084008_14, 2012/08

 Times Cited Count:73 Percentile:6.16(Physics, Applied)

Various kinds of energetic particles are irradiated into iron-based superconductors, and their effects on the critical current density $$J$$$$_{rm c}$$ and vortex dynamics have been systematically studied. It is found that $$J$$$$_{rm c}$$ is enhanced and vortex dynamics is strongly suppressed by energetic particles having a sufficient energy deposition rate, similar to the case of high temperature cuprate superconductors. The enhancement of $$J$$$$_{rm c}$$, in general, persists up to much higher irradiation doses than in cuprates. However, details of the effect of irradiation depend on the kind of ion species and their energies. Even with the same ions and energies, the effect is not universal for different kinds of iron-based superconductors. The correlated nature of defects created by heavy-ion irradiation is confirmed by the angular dependence of irreversible magnetization.

Journal Articles

Low-field anomaly of vortex dynamics in iron-pnictide superconductors

Tamegai, Tsuyoshi*; Taen, Toshihiro*; Yagyuda, Hidenori*; Nakajima, Yasuyuki*; Okayasu, Satoru; Sasase, Masato*; Kitamura, Hisashi*; Murakami, Takeshi*; Kambara, Tadashi*; Kanai, Yasuyuki*

Physica C, 471, p.777 - 780, 2011/00

 Times Cited Count:6 Percentile:67.5(Physics, Applied)

Magnetic relaxations in Ba(Fe$$_{1-x}$$Co$$_{x}$$)$$_{2}$$As$$_{2}$$ before and after swift particle irradiations are measured. The normalized relaxation rate S shows a clear suppression in a pristine sample at low fields below the self-field. Heavy-ion irradiations suppress these anomalies considerably, although there still remain weak features depending on ion species and/or energies. In a proton irradiated sample, the low-field anomaly of S survives although it is smeared compared with that in a pristine sample. All these results indicate that the low-field anomaly of S is suppressed by defects, and correlated defects have stronger effects.

Journal Articles

Modification of Fe-Pd invar alloys by high-energy heavy ions

Ono, Fumihisa*; Chimi, Yasuhiro; Ishikawa, Norito; Kanamitsu, Hiroaki*; Matsushima, Yasushi*; Iwase, Akihiro*; Kambara, Tadashi*

Nuclear Instruments and Methods in Physics Research B, 257(1-2), p.402 - 405, 2007/04

 Times Cited Count:5 Percentile:57.16(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Swift heavy ion irradiation effects in nanocrystalline gold

Chimi, Yasuhiro; Iwase, Akihiro*; Ishikawa, Norito; Kobiyama, Mamoru*; Inami, Takashi*; Kambara, Tadashi*; Okuda, Shigeo*

Nuclear Instruments and Methods in Physics Research B, 245(1), p.171 - 175, 2006/04

 Times Cited Count:13 Percentile:30.44(Instruments & Instrumentation)

We have studied effects of irradiation with energetic particles on defect accumulation in nanocrystalline gold (nano-Au). The specimens of nano-Au foil (3-5 $$mu$$m thickness) with various grain sizes (23-156 nm) are prepared by the gas deposition method and subsequent thermal annealings. Irradiations of the specimens with 60-MeV $$^{12}$$C ions, 3.54-GeV $$^{136}$$Xe ions or 2.0-MeV electrons are performed at low temperature. The defect accumulation behavior is observed by measuring the electrical resistivity change during irradiation. Through an analysis of defect accumulation behavior, cross-sections for defect production, $$sigma$$$$_{d}$$, and annihilation, $$sigma$$$$_{r}$$, in nano-Au increase monotonically as the grain size decreases. These results are considered to be caused by the existence of a large volume fraction of the regions near grain boundaries in nano-Au where the threshold energy for atomic displacements, E$$_{d}$$, becomes lower than in polycrystalline gold. The possibility of electronic excitation effects in nano-Au is also discussed.

Journal Articles

Effect of high-energy ion irradiation on magnetic properties in Fe-Pt invar alloys

Ono, Fumihisa*; Kanamitsu, Hiroaki*; Matsushima, Yasushi*; Chimi, Yasuhiro; Ishikawa, Norito; Kambara, Tadashi*; Iwase, Akihiro*

Nuclear Instruments and Methods in Physics Research B, 245(1), p.166 - 170, 2006/04

 Times Cited Count:4 Percentile:64.34(Instruments & Instrumentation)

Specimens of both ordered and disordered Fe-28.3at.%Pt alloys were irradiated with 200-MeV Xe ions to the fluence of 10$$^{14}$$ ions/cm$$^{2}$$. Measurements of AC-susceptibility-temperature curves were made for each specimen before and after the irradiation by using a specially designed apparatus for rapid measurements. In contrast to the expectation from the previous results for Fe-Ni alloys, in disordered Fe-Pt invar alloy the Curie temperature, T$$_{C}$$ decreased about 15 K by the irradiation. This fact cannot be explained by considering the lattice expansion effect alone. In Fe-Pt invar alloys the effect of lattice expansion may be cancelled out by some other effects which may be originated from the large difference in atomic mass between the two elements. For ordered Fe-Pt alloy, T$$_{C}$$ decreased as large as 60 K with the same fluence. The value of T$$_{C}$$ for both ordered and disordered Fe-Pt invar alloys coincide with each other after the irradiation. This fact can be explained by considering that the ordered state becomes disordered by the irradiation.

Journal Articles

Pressure dependence of the irradiation-induced ferromagnetism in Fe-Ni invar alloys

Matsushima, Yasushi*; Sun, N. Q.*; Kanamitsu, Hiroaki*; Matsushita, Masafumi*; Iwase, Akihiro*; Chimi, Yasuhiro; Ishikawa, Norito; Kambara, Tadashi*; Ono, Fumihisa*

Journal of Magnetism and Magnetic Materials, 298(1), p.14 - 18, 2006/03

 Times Cited Count:6 Percentile:66.89(Materials Science, Multidisciplinary)

Pressure dependence of the irradiation-induced ferromagnetism recently found in Fe-Ni invar alloys was investigated under hydrostatic pressures up to 7.5 GPa. A rectangular sheet of Fe-30.2at% Ni invar alloy was irradiated with 80-MeV Xe ions. The range was much smaller than the thickness of the sample. The Curie temperature of the irradiated part increased by 63 K, and the absolute value of the pressure coefficient, d$$T$$$$_{rm c}$$/d$$p$$ was smaller than that of non-irradiated part. The relation $$p$$ $$approx$$ ($$T$$$$_{rm c0}$$ - $$T$$$$_{rm c}$$)$$^{n}$$ holds with n = 2 for both non-irradiated and irradiated part. The itinerant character was not so much modified by irradiation.

Journal Articles

Anomalous shift of Curie temperature in iron-nickel invar alloys by high-energy heavy ion irradiation

Iwase, Akihiro; Hamatani, Yutaro*; Mukumoto, Yoshinori*; Ishikawa, Norito; Chimi, Yasuhiro; Kambara, Tadashi*; M$"u$ller, C.*; Neumann, R.*; Ono, Fumihisa*

Nuclear Instruments and Methods in Physics Research B, 209(1-4), p.323 - 328, 2003/08

 Times Cited Count:18 Percentile:23.17(Instruments & Instrumentation)

Fe=Ni Invar alloy is irradiated with GeV Xe and U ions at room temperature. By the irradiation, the Curie temperature of the soecimens increases, which is correlated with the electronic stopping power. This phenomenon can be explained as due to the lattice expansion and/or the local increase in Ni concentration.

Journal Articles

Hardening of Fe-Cu alloys by swift heavy ion irradiation

Iwase, Akihiro; Hasegawa, Tadayuki*; Chimi, Yasuhiro; Tobita, Toru; Ishikawa, Norito; Suzuki, Masahide; Kambara, Tadashi*; Ishino, Shiori*

Nuclear Instruments and Methods in Physics Research B, 195(3-4), p.309 - 314, 2002/10

 Times Cited Count:12 Percentile:36.53(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Irradiation effects on MgB$$_{2}$$ bulk samples and formation of columner defects on high-Tc supercoductor

Okayasu, Satoru; Sasase, Masato; Hojo, Kiichi; Chimi, Yasuhiro; Iwase, Akihiro; Ikeda, Hiroshi*; Yoshizaki, Ryozo*; Kambara, Tadashi*; Sato, H.*; Hamatani, Yutaro*; et al.

Physica C, 382(1), p.104 - 107, 2002/10

 Times Cited Count:26 Percentile:24.85(Physics, Applied)

no abstracts in English

Journal Articles

Defect production induced by electronic excitation in iron

Chimi, Yasuhiro; Iwase, Akihiro; Ishikawa, Norito; Kambara, Tadashi*

Nuclear Instruments and Methods in Physics Research B, 193(1-4), p.248 - 252, 2002/06

 Times Cited Count:2 Percentile:80.04(Instruments & Instrumentation)

no abstracts in English

Journal Articles

${it S}$$$_{e}$$-scaling of lattice parameter change in high ion-velocity region (${it v}$ $$geq$$ 2.6$$times$$10$$^{9}$$ cm/s) in ion-irradiated EuBa$$_{2}$$Cu$$_{3}$$O$$_{y}$$

Ishikawa, Norito; Iwase, Akihiro; Chimi, Yasuhiro; Michikami, Osamu*; Wakana, Hironori*; Hashimoto, Takeo*; Kambara, Tadashi*; M$"u$ller, C.*; Neumann, R.*

Nuclear Instruments and Methods in Physics Research B, 193(1-4), p.278 - 282, 2002/06

 Times Cited Count:7 Percentile:53.58(Instruments & Instrumentation)

Swift heavy ions with wide energy range of 80MeV-3.84GeV have been irradiated to EuBa$$_{2}$$Cu$$_{3}$$O$$_{y}$$ oxide superconductors, and the lattice parameter change due to elecronic excitation has been measured. In the high ion-velocity region, the change in lattice parameter per unit fluence varies as the 4th power of the electronic stopping power. However, in the low-velocity region, the deviation from the 4th power dependence is observed. The results are analyzed by using the primary ionization rate, and it is found that the results support that the Coulomb explosion triggers the atomic displacements.

Journal Articles

Pinning properties of quenched and melt growth method-YBCO bulk samples

Okayasu, Satoru; Sasase, Masato; Kuroda, N.; Iwase, Akihiro; Kazumata, Yukio*; Kambara, Tadashi*

Physica C, 357-360(Part.1), p.501 - 504, 2001/09

no abstracts in English

Journal Articles

Effects of defect morphology on the properties of vortex system in Bi$$_{2}$$Sr$$_{2}$$CaCu$$_{2}$$O$$_{8+delta}$$ irradiated with GeV heavy ions

Kuroda, N.; Ishikawa, Norito; Chimi, Yasuhiro; Iwase, Akihiro; Ikeda, Hiroshi*; Yoshizaki, Ryozo*; Kambara, Tadashi*

Physical Review B, 63(22), p.224502_1 - 224502_5, 2001/06

 Times Cited Count:6 Percentile:61.25(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Defect production induced by primary ionization in ion-irradiated oxide superconductors

Ishikawa, Norito; Iwase, Akihiro; Chimi, Yasuhiro; Michikami, Osamu*; Wakana, Hironori*; Kambara, Tadashi*

Journal of the Physical Society of Japan, 69(11), p.3563 - 3575, 2000/11

 Times Cited Count:7 Percentile:48.95(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Radiation annealing induced by electronic excitation in iron

Chimi, Yasuhiro; Iwase, Akihiro; Ishikawa, Norito; Kuroda, N.; Kambara, Tadashi*

Nuclear Instruments and Methods in Physics Research B, 164-165, p.408 - 414, 2000/04

 Times Cited Count:6 Percentile:54.61(Instruments & Instrumentation)

no abstracts in English

Journal Articles

Recoupling vortices due to columnar defects in 3.5GeV Xe-irradiated QMG-YBCO

Okayasu, Satoru; Kuroda, N.*; Iwase, Akihiro; Kambara, Tadashi*

Advances in Superconductivity XI, p.287 - 290, 1999/00

no abstracts in English

Journal Articles

Ion-velocity effects on defect production in high-T$$_{c}$$ superconductors and metals irradiated with swift heavy ions

Ishikawa, Norito; Chimi, Yasuhiro; Kuroda, N.*; Iwase, Akihiro; Kambara, Tadashi*

Phys. Scr., T80(B), p.559 - 561, 1999/00

 Times Cited Count:3 Percentile:66.03(Physics, Multidisciplinary)

no abstracts in English

Journal Articles

Vortex dynamics in Bi$$_{2}$$(Sr,La)$$_{2}$$CuO$$_{6+delta}$$ and Bi$$_{2}$$Sr$$_{2}$$CaCu$$_{2}$$O$$_{8+delta}$$ single crystals with columnar defects

Kuroda, N.; Ishikawa, Norito; Chimi, Yasuhiro; Iwase, Akihiro; Okayasu, Satoru; Ikeda, Hiroshi*; Yoshizaki, Ryozo*; Kambara, Tadashi*

Physica C, 321(3-4), p.143 - 150, 1999/00

 Times Cited Count:11 Percentile:44.12(Physics, Applied)

no abstracts in English

Journal Articles

Electronic excitation effects in ion-irradiated high-Tc superconductors

Ishikawa, Norito; Chimi, Yasuhiro; Iwase, Akihiro; Maeta, Hiroshi; *; Michikami, Osamu*; Kambara, Tadashi*; *; *; Terasawa, M.*

Nuclear Instruments and Methods in Physics Research B, 135, p.184 - 189, 1998/00

 Times Cited Count:13 Percentile:27.17(Instruments & Instrumentation)

no abstracts in English

Journal Articles

High energy heavy ion irradiation damage in oxide superconductor EuBa$$_{2}$$Cu$$_{3}$$O$$_{y}$$

Iwase, Akihiro; Ishikawa, Norito; Chimi, Yasuhiro; Wakana, Hironori*; Michikami, Osamu*; Kambara, Tadashi*; *

Nuclear Instruments and Methods in Physics Research B, 146(1-4), p.557 - 564, 1998/00

 Times Cited Count:16 Percentile:22.03(Instruments & Instrumentation)

no abstracts in English

30 (Records 1-20 displayed on this page)