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Suzuki, Kazuya; Mizukami, Shigemi*
AIP Advances (Internet), 13(3), p.035225_1 - 035225_6, 2023/03
Times Cited Count:0We studied MgO barrier magnetic tunnel junctions (MTJs) comprising perpendicularly magnetized MnGa and FeCoB electrodes. In those perpendicular (-) MTJs, we utilized thin metastable bcc CoMn alloys for an interlayer between MnGa and MgO to enhance the tunnel magnetoresistance (TMR). Moreover, we investigated the effect of a thin Mg interlayer between MnGa and CoMn. Owing to the interlayer engineering, we achieved a TMR ratio over 100%, the highest value observed for
-MTJs with a tetragonal MnGa electrode. Our study contributes to the further development of spintronic devices using
-MTJs with various Mn-based tetragonal alloy electrodes.
Honda, Mitsunori; Kaneta, Yui; Yaita, Tsuyoshi
AIP Advances (Internet), 13(1), p.015314_1 - 015314_6, 2023/01
Times Cited Count:0 Percentile:0.01(Nanoscience & Nanotechnology)The efficiency of the sorption of Sr on weathered biotite, a type of clay minerals was investigated. Removal of Sr
and Cs
is important in the treatment of contaminated water from the 1F accident, which is one of the radionuclide waste treatment problems. We focused on developing an adsorption method for Sr ions using weathered biotite, which are abundant in Fukushima. Applying a molten salt treatment, the amount of sorbed Sr
simply increased as the added mass ratio of strontium chloride (SrCl
) increased from 1:1, 1:5, and 1:10 for the one-fold, five-fold, and ten-fold additions of SrCl
, respectively. Then, the crystal structure of weathered biotite as an adsorbent was evaluated by X-ray diffraction (XRD) analysis. Thus, it was observed that the WB retained its original crystal structure even after the sorption of Sr
. Extended X-ray absorption fine structure (EXAFS) analysis was performed to investigate the local sorption structure of Sr
in the WB. The results revealed that Sr
was preferentially sorbed into the SiO
and Al
O
layers when Sr
was in the low mass ratio, while, it was mainly sorbed into the SiO
layer when the ratio was high.
Matsuya, Yusuke; Kusumoto, Tamon*; Yachi, Yoshie*; Hirata, Yuho; Miwa, Misako*; Ishikawa, Masayori*; Date, Hiroyuki*; Iwamoto, Yosuke; Matsuyama, Shigeo*; Fukunaga, Hisanori*
AIP Advances (Internet), 12(2), p.025013_1 - 025013_9, 2022/02
Times Cited Count:2 Percentile:66.83(Nanoscience & Nanotechnology)Boron Neutron Capture Therapy (BNCT) is a radiation therapy, which can selectively eradicate solid tumors by -particles and Li ions generated through the nuclear reaction between thermal neutron and
B in tumor cells. With the development of accelerator-based neutron sources that can be installed in medical institutions, accelerator-based boron neutron capture therapy is expected to become available at several medical institutes around the world in the near future. Lithium is one of the targets that can produce thermal neutrons from the
Li(p,n)
Be near-threshold reaction. Particle and Heavy Ion Transport code System (PHITS) is a general-purpose Monte Carlo code, which can simulate a variety of diverse particle types and nuclear reactions. The latest PHITS code enables simulating the generation of neutrons from the
Li(p,n)
Be reactions by using Japanese Evaluated Nuclear Data Library (JENDL-4.0/HE). In this study, we evaluated the neutron fluence using the PHITS code by comparing it to reference data. The subsequent neutron transport simulations were also performed to evaluate the boron trifluoride (BF
) detector responses and the recoiled proton fluence detected by a CR-39 plastic detector. As a result, these comparative studies confirmed that the PHITS code can accurately simulate neutrons generated from an accelerator using a Li target. The PHITS code has a significant potential for contributing to more precise evaluating accelerator-based neutron fields and understandings of therapeutic effects of BNCT.
Kumazoe, Hiroyuki*; Igarashi, Yasuhiko*; Iesari, F.*; Shimizu, Ryota*; Komatsu, Yuya*; Hitosugi, Taro*; Matsumura, Daiju; Saito, Hiroyuki*; Iwamitsu, Kazunori*; Okajima, Toshihiko*; et al.
AIP Advances (Internet), 11(12), p.125013_1 - 125013_5, 2021/12
Times Cited Count:1 Percentile:14.03(Nanoscience & Nanotechnology)Yoon, J.-Y.*; Takeuchi, Yutaro*; DuttaGupta, S.*; Yamane, Yuta*; Kanai, Shun*; Ieda, Junichi; Ohno, Hideo*; Fukami, Shunsuke*
AIP Advances (Internet), 11(6), p.065318_1 - 065318_6, 2021/06
Times Cited Count:10 Percentile:79.5(Nanoscience & Nanotechnology)Suzudo, Tomoaki; Tsuru, Tomohito
AIP Advances (Internet), 11(6), p.065012_1 - 065012_7, 2021/06
Times Cited Count:2 Percentile:28.94(Nanoscience & Nanotechnology)In the current study, we analyzed the self-interstitial atoms (SIAs) in BCC molybdenum (Mo) and tungsten (W) in comparison with other BCC transition metals utilizing first-principles method; particularly, we focused on uncommon dumbbells, whose direction are inclined from 111
toward
110
on the {110} plane. Such a direction is not stable neither in the group 5 BCC metals (i.e., vanadium, niobium, and tantalum) nor in
-iron. Our first-principles relaxation simulations indicated that inclined dumbbells were more energetically-favored than common
111
dumbbells in Mo, while this is not necessarily the case for W. However, under a certain degree of lattice strain, such as shear or expansive strain, could make inclined dumbbells more favored also in W, suggesting that the lattice strain can substantially influence the migration barrier of SIAs in these metals because inclined dumbbells generally have a larger migration barrier than
111
dumbbells.
Nakazawa, Tetsuya
AIP Advances (Internet), 11(4), p.045032_1 - 045032_8, 2021/04
Times Cited Count:0 Percentile:0(Nanoscience & Nanotechnology)Geometries and energy separations of various low-lying electronic states of iron trimer (Fe) are investigated by CCSD and CCSD(T) calculations. The ground state is found to be a
A' state with C
symmetry, whereas a nearly isoenergetic state,
A
(C
), is degenerate to the ground state. The ground and five low-lying states with a spin multiplicity of 13 are found below 0.20 eV at the CCSD(T) level. On the other hand, the low-lying states with spin multiplicities of 9, 11, and 15 appear only above 0.20 eV. From detailed natural bond orbital (NBO) analyses, Fe
has Fe-Fe bonds comprised of
-bond orbitals only in
-spin part with higher s-character in low-lying states with a spin multiplicity of 13. The polarization coefficients indicate that the
bonds are nearly complete covalent bonds with little polarization.
Suzudo, Tomoaki; Ebihara, Kenichi; Tsuru, Tomohito
AIP Advances (Internet), 10(11), p.115209_1 - 115209_8, 2020/11
Times Cited Count:6 Percentile:41.49(Nanoscience & Nanotechnology)The mechanism of their brittle fracture of BCC metals is not fully understood. In this study, we conduct a series of three-dimensional molecular dynamics simulations of cleavage fracture of -iron. In particular, we focus on mode-I loading starting from curved crack fronts. In the simulations, brittle fractures are observed at cleavages on the {100} plane, while the initial cracks become blunted on other planes as a result of dislocation emissions. Our modeling results agreed with a common experimental observation, that is, {100} is the preferential cleavage plane in bcc transition metals.
Hayashi, Kei*; Saito, Wataru*; Sugimoto, Kazuya*; Oyama, Kenji*; Hayashi, Koichi*; Happo, Naohisa*; Harada, Masahide; Oikawa, Kenichi; Inamura, Yasuhiro; Miyazaki, Yuzuru*
AIP Advances (Internet), 10(3), p.035115_1 - 035115_7, 2020/03
Times Cited Count:15 Percentile:76.81(Nanoscience & Nanotechnology)Oyanagi, Koichi*; Kikkawa, Takashi*; Saito, Eiji
AIP Advances (Internet), 10(1), p.015031_1 - 015031_5, 2020/01
Times Cited Count:13 Percentile:72.26(Nanoscience & Nanotechnology)Kubota, Masato; Nigo, Seisuke*; Kato, Seiichi*; Amemiya, Kenta*
AIP Advances (Internet), 9(9), p.095050_1 - 095050_4, 2019/09
Times Cited Count:0 Percentile:0(Nanoscience & Nanotechnology)We measured the X-ray absorption spectra of amorphous alumina with vacancy-type oxygen defects which exhibits the resistance random access memory effect. For the first time, we detected changes in the electronic structure owing to the memory effect. A major difference in spectrum was observed near the O K-absorption edge.
Osamura, Kozo*; Machiya, Shutaro*; Kajiwara, Kentaro*; Kawasaki, Takuro; Harjo, S.; Zhang, Y.*; Fujita, Shinji*; Iijima, Yasuhiro*; Hampshire, D. P.*
AIP Advances (Internet), 9(7), p.075216_1 - 075216_11, 2019/07
Times Cited Count:7 Percentile:43.45(Nanoscience & Nanotechnology)Saito, Yuika*; Tokiwa, Kenshiro*; Kondo, Takahiro*; Bao, J.*; Terasawa, Tomoo; Norimatsu, Wataru*; Kusunoki, Michiko*
AIP Advances (Internet), 9(6), p.065314_1 - 065314_6, 2019/06
Times Cited Count:2 Percentile:12.38(Nanoscience & Nanotechnology)Kubo, Katsunori
AIP Advances (Internet), 8(10), p.101313_1 - 101313_6, 2018/10
Times Cited Count:3 Percentile:16.95(Nanoscience & Nanotechnology)Ikeuchi, Kazuhiko*; Nakajima, Kenji; Kawamura, Seiko; Kajimoto, Ryoichi; Wakimoto, Shuichi; Suzuki, Kensuke*; Fujita, Masaki*
AIP Advances (Internet), 8(10), p.101318_1 - 101318_5, 2018/10
Times Cited Count:0 Percentile:0(Nanoscience & Nanotechnology)By means of inelastic neutron scattering, we measured magnetic excitations in a sizable single crystal of LaSr
Cu
Al
O
, which is an Al-substituted system of the heavily hole-doped cuprate system La
Sr
CuO
with an effective concentration of holes of
= 0.25.
Okuda, Tetsuji*; Kajimoto, Ryoichi; Noda, Masaaki*; Kuwahara, Hideki*
AIP Advances (Internet), 8(10), p.101339_1 - 101339_5, 2018/10
Times Cited Count:0 Percentile:0(Nanoscience & Nanotechnology)Hiraka, Haruhiro*; Oyama, Kenji*; Kosaka, Masashi*; Matsumura, Daiju
AIP Advances (Internet), 8(10), p.101424_1 - 101424_5, 2018/10
Times Cited Count:1 Percentile:5.11(Nanoscience & Nanotechnology)Okumura, Masahiko; Sassi, M.*; Rosso, K. M.*; Machida, Masahiko
AIP Advances (Internet), 7(5), p.055211_1 - 055211_9, 2017/05
Times Cited Count:6 Percentile:32.15(Nanoscience & Nanotechnology)no abstracts in English
Gu, B.; Maekawa, Sadamichi
AIP Advances (Internet), 7(5), p.055805_1 - 055805_6, 2017/05
Times Cited Count:4 Percentile:22.07(Nanoscience & Nanotechnology)Ramos, R.*; Kikkawa, Takashi*; Anadn, A.*; Lucas, I.*; Uchida, Kenichi*; Algarabel, P. A.*; Morell
n, L.*; Aguirre, M. H.*; Saito, Eiji; Ibarra, M. R.*
AIP Advances (Internet), 7(5), p.055915_1 - 055915_7, 2017/05
Times Cited Count:17 Percentile:65.69(Nanoscience & Nanotechnology)