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Ito, Takashi; Higemoto, Wataru; Koda, Akihiro*; Nakamura, Jumpei*; Shimomura, Koichiro*
Interactions (Internet), 245(1), p.25_1 - 25_7, 2024/12
Fujihara, Masayoshi; Okabe, Hirotaka*; Koda, Akihiro*
Interactions (Internet), 245(1), p.13_1 - 13_6, 2024/12
Quantum states are difficult to observe experimentally. In addition, ideal model materials have not been found for some of the lattice systems in which exotic quantum states are predicted to be realized. Numerous candidates for low-dimensional quantum magnets are hidden in copper minerals, and the number of candidates is increasing every year. We succeeded to synthesize seven copper minerals by imitating the environment where they are discovered and reported their quantum states. The properties of pulsed muons are very suitable for investigating the spin state of artificial copper minerals.
Shimomura, Koichiro*; Koda, Akihiro*; Pant, A. D.*; Sunagawa, Hikaru*; Fujimori, Hiroshi*; Umegaki, Izumi*; Nakamura, Jumpei*; Fujihara, Masayoshi; Tampo, Motonobu*; Kawamura, Naritoshi*; et al.
Interactions (Internet), 245(1), p.31_1 - 31_6, 2024/12
Kadono, Ryosuke*; Hiraishi, Masatoshi*; Okabe, Hirotaka*; Koda, Akihiro*; Ito, Takashi
Journal of Physics; Condensed Matter, 35(28), p.285503_1 - 285503_13, 2023/07
Times Cited Count:0 Percentile:0(Physics, Condensed Matter)Oishi, Kazuki*; Igarashi, Daisuke*; Tatara, Ryoichi*; Kawamura, Yukihiko*; Hiroi, Kosuke; Suzuki, Junichi*; Umegaki, Izumi*; Nishimura, Shoichiro*; Koda, Akihiro*; Komaba, Shinichi*; et al.
Journal of Physics; Conference Series, 2462, p.012048_1 - 012048_5, 2023/03
Times Cited Count:0 Percentile:0.2(Physics, Applied)Shimomura, Koichiro*; Koda, Akihiro*; Pant, A. D.*; Natori, Hiroaki*; Fujimori, Hiroshi*; Umegaki, Izumi*; Nakamura, Jumpei*; Tampo, Motonobu*; Kawamura, Naritoshi*; Teshima, Natsuki*; et al.
Journal of Physics; Conference Series, 2462, p.012033_1 - 012033_5, 2023/03
Times Cited Count:0 Percentile:0.2(Physics, Applied)Fujihara, Masayoshi; Hagihara, Masato; Morita, Katsuhiro*; Murai, Naoki; Koda, Akihiro*; Okabe, Hirotaka*; Mitsuda, Setsuo*
Physical Review B, 107(5), p.054435_1 - 054435_8, 2023/02
Times Cited Count:0 Percentile:0(Materials Science, Multidisciplinary)The = 1/2 Heisenberg linear chain antiferromagnet is the simplest spin model; nevertheless it serves as a platform for various quantum many-body phenomena. Here, we report the magnetic behavior of a quasi-one-dimensional antiferromagnet KCuPOHO. A long-range commensurate antiferromagnetic order with ordered moment 0.31(1) per spin occurs at = 11.7(1) K. Above , the inelastic neutron excitation is characterized by a two spinon continuum. The intrachain interaction and interchain interaction are estimated to be 172 K and 4.25(4) K, respectively; thus the ratio of the / = 0.0247(3). At lower energies, below , a spin gap is observed in the dispersive excitations. These results are consistent with characteristics observed in weakly interacting = 1/2 Heisenberg chain system.
Fujihara, Masayoshi; Jeschke, H. O.*; Morita, Katsuhiro*; Kuwai, Tomohiko*; Koda, Akihiro*; Okabe, Hirotaka*; Matsuo, Akira*; Kindo, Koichi*; Mitsuda, Setsuo*
Physical Review Materials (Internet), 6(11), p.114408_1 - 114408_8, 2022/11
Times Cited Count:0 Percentile:0(Materials Science, Multidisciplinary)= 1/2 Heisenberg - chain antiferromagnets have been investigated extensively due to their exotic magnetic states. Here, we report the magnetic behavior of birchite CdCu(PO)SO5HO and its effective spin model. Experimental studies by magnetic susceptibility, magnetization, heat capacity, and SR measurements indicate the absence of long-range order down to 0.4 K. Theoretical studies reveal that birchite is a model compound for the - antiferromagnetic chain: the intrachain interactions and are antiferromagnetic and their magnitude is about 100 times larger than the interchain interactions. The magnitude of is two to three times larger than that of , thus the spin gap is expected to be only a few percent of that of . The temperature dependence of the specific heat shows a broad peak at about 1 K ( 0.036 ), which suggests the presence of a spin gap.
Okuma, Ryutaro*; Kofu, Maiko; Asai, Shinichiro*; Avdeev, M.*; Koda, Akihiro*; Okabe, Hirotaka*; Hiraishi, Masatoshi*; Takeshita, Soshi*; Kojima, Kenji*; Kadono, Ryosuke*; et al.
Nature Communications (Internet), 12, p.4382_1 - 4382_7, 2021/07
Times Cited Count:6 Percentile:61.42(Multidisciplinary Sciences)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
Times Cited Count:2 Percentile:17.84(Materials Science, Multidisciplinary)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.
Fujihara, Masayoshi*; Morita, Katsuhiro*; Mole, R.*; Mitsuda, Setsuo*; Toyama, Takami*; Yano, Shinichiro*; Yu, D.*; Sota, Shigetoshi*; Kuwai, Tomohiko*; Koda, Akihiro*; et al.
Nature Communications (Internet), 11, p.3429_1 - 3429_7, 2020/07
Times Cited Count:37 Percentile:90.63(Multidisciplinary Sciences)Ito, Takashi; Higemoto, Wataru; Koda, Akihiro*; Shimomura, Koichiro*
Applied Physics Letters, 115(19), p.192103_1 - 192103_4, 2019/11
Times Cited Count:8 Percentile:37.59(Physics, Applied)Iida, Kazuki*; Yoshida, Hiroyuki*; Okabe, Hirotaka*; Katayama, Naoyuki*; Ishii, Yuto*; Koda, Akihiro*; Inamura, Yasuhiro; Murai, Naoki; Ishikado, Motoyuki*; Kadono, Ryosuke*; et al.
Scientific Reports (Internet), 9(1), p.1826_1 - 1826_9, 2019/02
Times Cited Count:9 Percentile:59.53(Multidisciplinary Sciences)Strasser, P.*; Abe, Mitsushi*; Aoki, Masaharu*; Choi, S.*; Fukao, Yoshinori*; Higashi, Yoshitaka*; Higuchi, Takashi*; Iinuma, Hiromi*; Ikedo, Yutaka*; Ishida, Katsuhiko*; et al.
EPJ Web of Conferences, 198, p.00003_1 - 00003_8, 2019/01
Times Cited Count:13 Percentile:99.06(Quantum Science & Technology)Sugiyama, Jun*; Umegaki, Izumi*; Nozaki, Hiroshi*; Higemoto, Wataru; Hamada, Koji*; Takeshita, Soshi*; Koda, Akihiro*; Shimomura, Koichiro*; Ninomiya, Kazuhiko*; Kubo, Kenya*
Physical Review Letters, 121(8), p.087202_1 - 087202_5, 2018/08
Times Cited Count:18 Percentile:74.47(Physics, Multidisciplinary)Kawamura, Seiko; Tomiyasu, Keisuke*; Koda, Akihiro*; Sari, D. P.*; Asih, R.*; Yoon, S.*; Watanabe, Isao*; Nakajima, Kenji
JPS Conference Proceedings (Internet), 21, p.011007_1 - 011007_5, 2018/03
RbCuMoO is a one-dimensional quantum spin system with spin frustration. The magnetic ground state of this system has been expected to be incommensurate spin-singlet from a theoretical study. Furthermore, it was recently reported that this system exhibited ferroelectricity under a magnetic field. We carried out SR studies on this system to understand the magnetic properties. A slow muon spin relaxation due to nuclear dipoles is observed in the whole measured temperatures ranging from 0.06 K to 250 K, indicating that no magnetic ordering. The result suggests that the system shows a spin-singlet ground state. Furthermore, it was found that the distribution of the internal magnetic field were slightly enhanced below 10 K. This temperature dependence resembles that of the electric polarization observed in the magnetic field. It may indicate that some local anomaly of charge/spin related to the ferroelectricity is detected by a microscopic probe.
Ueno, Yasuhiro*; Aoki, Masaharu*; Fukao, Yoshinori*; Higashi, Yoshitaka*; Higuchi, Takashi*; Iinuma, Hiromi*; Ikedo, Yutaka*; Ishida, Katsuhiko*; Ito, Takashi; Iwasaki, Masahiko*; et al.
Hyperfine Interactions, 238(1), p.14_1 - 14_6, 2017/11
Times Cited Count:3 Percentile:86.59(Physics, Atomic, Molecular & Chemical)Higemoto, Wataru; Kadono, Ryosuke*; Kawamura, Naritoshi*; Koda, Akihiro*; Kojima, Kenji*; Makimura, Shunsuke*; Matoba, Shiro*; Miyake, Yasuhiro*; Shimomura, Koichiro*; Strasser, P.*
Quantum Beam Science (Internet), 1(1), p.11_1 - 11_24, 2017/06
A muon experimental facility, known as the Muon Science Establishment (MUSE), is one of the user facilities at the Japan Proton Accelerator Research Complex, along with those for neutrons, hadrons, and neutrinos. The MUSE facility is integrated into the Materials and Life Science Facility building in which a high-energy proton beam that is shared with a neutron experiment facility delivers a variety of muon beams for research covering diverse scientific fields. In this review, we present the current status of MUSE, which is still in the process of being developed into its fully fledged form.
Ito, Takashi; Koda, Akihiro*; Shimomura, Koichiro*; Higemoto, Wataru; Matsuzaki, Teiichiro*; Kobayashi, Yoji*; Kageyama, Hiroshi*
Physical Review B, 95(2), p.020301_1 - 020301_5, 2017/01
Times Cited Count:11 Percentile:48.83(Materials Science, Multidisciplinary)Strasser, P.*; Aoki, Masaharu*; Fukao, Yoshinori*; Higashi, Yoshitaka*; Higuchi, Takashi*; Iinuma, Hiromi*; Ikedo, Yutaka*; Ishida, Katsuhiko*; Ito, Takashi; Iwasaki, Masahiko*; et al.
Hyperfine Interactions, 237(1), p.124_1 - 124_9, 2016/12
Times Cited Count:7 Percentile:90.97(Physics, Atomic, Molecular & Chemical)