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BaCo(PO
)Sheng, J.*; Wang, L.*; Candini, A.*; Jiang, W.*; Huang, L.*; Xi, B.*; Zhao, J.*; Ge, H.*; Zhao, N.*; Fu, Y.*; et al.
Proceedings of the National Academy of Sciences of the United States of America, 119(51), p.e2211193119_1 - e2211193119_9, 2022/12
Times Cited Count：3 Percentile：28(Multidisciplinary Sciences)Cu(PO)SO 
5HO as a model antiferromagnetic spin-1/2 Heisenberg 
- chainFujihara, 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.
O
Soda, Minoru*; Kofu, Maiko; Kawamura, Seiko; Asai, Shinichiro*; Masuda, Takatsugu*; Yoshizawa, Hideki*; Furukawa, Hazuki*
Journal of the Physical Society of Japan, 91(9), p.094707_1 - 094707_5, 2022/09
Times Cited Count：0 Percentile：0(Physics, Multidisciplinary)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)
PdSi
Hirschberger, M.*; Nakajima, Taro*; Kriener, M.*; Kurumaji, Takashi*; Spitz, L.*; Gao, S.*; Kikkawa, Akiko*; Yamasaki, Yuichi*; Sagayama, Hajime*; Nakao, Hironori*; et al.
Physical Review B, 101(22), p.220401_1 - 220401_6, 2020/06
Times Cited Count：40 Percentile：91.78(Materials Science, Multidisciplinary)Nakano, Hiroki*; Sakai, Toru
Journal of Physics; Conference Series, 868, p.012006_1 - 012006_10, 2017/07
Times Cited Count：3 Percentile：78.7(Physics, Applied)The spin gap issue of the kagome lattice antiferromagnet is investigated by the finite size scaling analysis applied for the energy spectrum of the rhombic clusters calculated by the numerical exact diagonalization. The conclusion is that the kagome lattice antiferromagnet is gapless, as well as the triangular lattice one.
Okamoto, Kiyomi*; Tonegawa, Takashi*; Sakai, Toru
Journal of Physics; Conference Series, 683(1), p.012038_1 - 012038_6, 2016/02
Times Cited Count：2 Percentile：69.93(Materials Science, Multidisciplinary)By use of mainly the exact diagonalization and the level spectroscopy method, we investigate the ground-state phase diagrams of the S=1/2 distorted diamond type quantum spin chain with the monomer-monomer interactions and ferromagnetic interactions. The magnetization plateau at 1/3 of the saturation magnetization was revealed to vanish in the region where the ferromagnetic interaction is rather strong.
Sakai, Toru; Nakano, Hiroki*
Physics Procedia, 75, p.369 - 375, 2015/12
Times Cited Count：1 Percentile：46.45(Physics, Applied)The S=1/2 three-leg quantum spin tube is investigated using the numerical diagonalization. The study indicated a new quantum phase transition between the 1/3 magnetization plateau phase and the plateauless one, with respect to the spin anisotropy. The phase diagram is also presented.
Sakai, Toru; Nakano, Hiroki*
Physics Procedia, 75, p.821 - 828, 2015/12
Times Cited Count：0 Percentile：0.04(Physics, Applied)The magnetization process of the S=1/2 kagome-lattice antiferromagnet is investigated using the numerical diagonalization up to 42-spin clusters. The critical exponent analysis confirms the unconventional magnetization behavior around the 1/3 magnetization plateau-like anomaly; the field derivative is infinite at the low-field side, while it is zero at the high-field side. We also confirm that a magnetization jump appears at 1/3 of the saturation magnetization in distorted kagome-lattice antiferromagnets.
Nakano, Hiroki*; Hasegawa, Yasumasa*; Sakai, Toru
Journal of the Physical Society of Japan, 84(11), p.114703_1 - 114703_6, 2015/11
Times Cited Count：33 Percentile：82.51(Physics, Multidisciplinary)The magnetization process of the spin-1/2 Heisenberg antiferromagnet on the distorted square-kagome lattice is investigated by the large-scale numerical diagonalization method. It is found that a novel magnetization jump appears at 1/3 of the saturation magnetization.
Sakai, Toru; Hijii, Keigo*; Okubo, Susumu*; Ota, Hitoshi*; Nakano, Hiroki*; Miyashita, Seiji*
Applied Magnetic Resonance, 46(9), p.997 - 1002, 2015/09
Times Cited Count：1 Percentile：6.49(Physics, Atomic, Molecular & Chemical)The S=1/2 kagome-lattice antiferromagnet is investigated by the numerical diagonalization of 18-spin finite-size cluster. The matrix elements proportional to the intensity of the singlet-triplet ESR transition are calculated in the presence of the Dzyaloshinsky-Moriya interaction. Some angle-dependent selection rules is also proposed.
=1/2 Heisenberg antiferromagnet in two dimensionsNakano, Hiroki*; Sakai, Toru
Japanese Journal of Applied Physics, 54(3), p.030305_1 - 030305_4, 2015/03
To clarify the instability of the ferrimagnetism which is the fundamental magnetism of ferrite, numerical diagonalization study for the two-dimensional =1/2 Heisenberg antiferromagnet with frustration. We find that the ferrimagnetic ground state has the spontaneous magnetization in small frustration.
Nakano, Hiroki*; Sakai, Toru
Japanese Journal of Applied Physics, 54(3), p.030305_1 - 030305_4, 2015/03
Times Cited Count：10 Percentile：41.41(Physics, Applied)To clarify the instability of the ferrimagnetism which is the fundamental magnetism of ferrite, numerical-diagonalization study is carried out for the two-dimensional S=1/2 Heisenberg antiferromagnet with frustration. We find that the ferrimagnetic ground state has the spontaneous magnetization in small frustration.
=1/2 kagome-lattice Heisenberg antiferromagnet at one-third height of the saturationNakano, Hiroki*; Sakai, Toru
Journal of the Physical Society of Japan, 83(10), p.104710_1 - 104710_7, 2014/09
Times Cited Count：34 Percentile：83.14(Physics, Multidisciplinary)The magnetization process of the =1/2 Heisenberg antiferromagnet on the kagome lattice is studied by the numerical diagonalization method. We successfully obtain a new result of the magnetization process of a 42-site cluster in the entire range. Our analysis clarifies that the critical behavior around one-third of the height of the saturation is different from the typical behavior of the well-known magnetization plateau in two-dimensional systems.
Onishi, Hiroaki; Hotta, Takashi
Physica B; Condensed Matter, 378-380, p.589 - 591, 2006/05
Times Cited Count：1 Percentile：6.64(Physics, Condensed Matter)We investigate the ground-state property of an 
-orbital Hubbard model at quarter filling on a zigzag chain by exploiting the density matrix renormalization group method. When two orbitals are degenerate, the zigzag chain is decoupled to a doble-chain spin system to suppress the spin frustration due to the spatial anisotropy of the occupied orbital. On the other hand, when the level splitting is increased and the orbital anisotropy disappears, a characteristic change in the spin incommensurability is observed due to the revival of the spin frustration.
OYoshii, Kenji; Ikeda, Naoshi*; Nakamura, Akio
Physica B; Condensed Matter, 378-380, p.585 - 586, 2006/05
Times Cited Count：39 Percentile：80.68(Physics, Condensed Matter)no abstracts in English
OIkeda, Naoshi*; Osumi, Hiroyuki*; Owada, Kenji; Ishii, Kenji; Inami, Toshiya; Kakurai, Kazuhisa; Murakami, Yoichi*; Yoshii, Kenji; Mori, Shigeo*; Horibe, Yoichi*; et al.
Nature, 436(7054), p.1136 - 1138, 2005/08
Times Cited Count：826 Percentile：99.77(Multidisciplinary Sciences)By means of resonant X-ray scattering experiments using synchrotron radiation of SPring-8, it was found that a mixed-valence system LuFeO is a ferroelectric material owing to a real-space charge-ordering of Fe
and Fe
. This ordering is rooted in a charge frustration between the Fe ions on a triangular lattice. The new mechanism of ferroelectricity shown in the present paper offers great potential for designing future ferroelectric devices to be coupled or controlled with the degrees of freedom of electron: charge, spin and orbital.
Onishi, Hiroaki; Hotta, Takashi
Physical Review B, 71(18), p.180410_1 - 180410_4, 2005/05
Times Cited Count：5 Percentile：26.14(Materials Science, Multidisciplinary)In order to clarify a crucial role of orbital degree of freedom in geometrically frustrated systems, we investigate both ground- and excited-state properties of the -orbital degenerate Hubbard model on two kinds of lattices, ladder and zigzag chain, by using numerical techniques. In the ladder, spin correlation extends on the whole system, while the zigzag chain is decoupled to a double chain and spin excitation is confined in one side of the double chain due to the selection of a specific orbital. We envision a kind of self-organization phenomenon that the geometrically frustrated multi-orbital system is spontaneously reduced to a one-orbital model to suppress the spin frustration.
Onishi, Hiroaki; Hotta, Takashi
Physica B; Condensed Matter, 359-361, p.669 - 671, 2005/04
Times Cited Count：3 Percentile：17(Physics, Condensed Matter)By using the density matrix renormalization group method, we investigate ground- and excited-state properties of the -orbital degenerate Hubbard model at quarter filling for two kinds of lattices, zigzag chain and ladder. In the zigzag chain, the system is effectively regarded as a decoupled double chain of the =1/2 antiferromagnetic Heisenberg model, and the spin gap is approximately zero, similar to the case of weakly coupled Heisenberg chains. On the other hand, in the ladder, the spin correlation on the rung remains robust and the spin gap exists.
O single crystalKamazawa, Kazuya*; Katano, Susumu; Tsunoda, Yorihiko*
Physica B; Condensed Matter, B345(1-4), p.96 - 98, 2004/03
Times Cited Count：5 Percentile：29.77(Physics, Condensed Matter)no abstracts in English
