X-ray-diffraction study of the periodic lattice distortion associated with a charge-density wave in 1T-VSe2

金沢大学理学

Remarkable crystalline electric field effect and very low-field metamagnetic transition in quasi-two-dimensional antiferromagnet Er5Ir4Si10 single crystal without geometrical magnetic frustration

金沢大学理工研究域数物科学

High temperature superconductor in the intermetallic compounds

金沢大学理工研究域数物科学系We have intensively investigated the superconducting properties of ternary suicide superconductor Sc5Ir4Si10 polycrystalline sample and antiferromagnetic transitions in ternary rare-earth metal silicide RsIr4Si10 (R= Tb, Dy, Ho, Er) single crystals by performing the high-resolution measurement of the low-temperature specific heat. We consider the antagonism between superconductivity and magnetism and conclude that the two-dimensional material which is containing the light elements undergoes superconductivity

Antiferromagnetic transition in ternary rare-earth metal silicide Er5Ir4Si10 single crystal

金沢大学理工研究域数物科学系We have precisely investigated the antiferromagnetic phase transition in the ternary rare-earth metal silicide Er5Ir4Si10 single crystal by performing the high-resolution measurement of the low-temperature specific heat under zero-magnetic field and the AC magnetization. In the temperature dependence of important physical quantities associated with the antiferromagnetic phase transition, we have observed anomalies associated with the antiferromagnetic long-range ordering at Neel temperature TN. We have confirmed that TN is 3.5 K. In addition, we have first observed two surprising results. Firstly, a shoulder was observed in the vicinity of 2 K in addition to the sharp peak at TN corresponding to the antiferromagnetic long-range ordering in the high-resolution measurement of the low-temperature specific heat. Secondly, the anomaly of the AC magnetization at TN depends on the magnetic field direction. Though we have clearly observed the anomaly of the AC magnetization associated with the antiferromagnetic phase transition at TN when the AC magnetic field direction is parallel to the c-axis, we have observed no anomaly of the AC magnetization at TN when the AC magnetic field orientation is perpendicular to the c-axis. These results clarify that our Er5Ir4Si10 single crystal is a quasi-two-dimensional antiferromagnet and then has no magnetic structure of the Er3+ local moments. However, we have observed a peak of the AC magnetization at around 2 K when the AC magnetic field is perpendicular to the c-axis. This temperature corresponds to that at which a shoulder is observed in the high-resolution measurement of the low-temperature specific heat. Furthermore, we have observed no frequency dependence of the AC magnetization which is ordinarily observed in the spin glass state. This result means that there is no disorder in our Er5Ir4Si10 single crystal because the crystal structure of Er5Ir4Si10 has the tetragonal crystal structure in which the octagons of Er3+ ions are stacked. In addition, both the tetragons and the octagons of Er3+ local moments have no magnetic frustration. At last, we can conclude that both the shoulder of the low-temperature specific heat in the vicinity of 2 K and the peak of the AC magnetization at around 2 K, which is only observed when the AC magnetic field direction is perpendicular to the c-axis, correspond to the crystalline electric field effect in the plane which is perpendicular to the c-axis of the tetragonal crystal structure. © 2008 Elsevier B.V. All rights reserved

Low-temperature specific heat study of antiferromagnetic transition in ternary rare-earth metal silicide R5Ir4Si10 (R = Tb, Dy, Ho, Er)

金沢大学理工研究域数物科学系We investigated antiferromagnetic transitions of R5lr4Si10 (R = Tb, Dy, Ho, Er) by measuring the low-temperature specific heat. The antiferromagnetic transition temperature TN is precisely determined. TN is l0.7 K for R = Tb, TN is 5.8 K for R = Dy, TN is 5.1 K for R = Ho and TN is 3.5 K for R = Er, respectively. These results suggest that the antiferromagnetic transition of the ternary rare-earth metal silicide R5lr4Si10 is dominated by the exchange interaction between R3+ ions like as the antiferromagnetic transitions in the ternary rare-earth metal compounds RCu2Ge2 (R = rare-earth metal). In addition, we report the upturn of the specific heat below 1.5 K observed for R = Tb and Ho. © 2006 Elsevier B.V. All rights reserved

Direct observation of remarkable crystalline-electric-field effect in quasi-two-dimensional antiferromagnet Er5Ir4Si10 single crystal by low-temperature specific heat

金沢大学理工研究域数物科学系We have intensively investigated the antiferromagnetic phase transition in the ternary rare-earth metal silicide Er5Ir4Si10 single crystal by performing the high-resolution measurement of the low-temperature specific heat under zero-magnetic field and the AC magnetization. In the temperature dependence of important physical quantities associated with the antiferromagnetic phase transition, we have observed anomalies with the antiferromagnetic long-range ordering at Neel temperature T N. We have confirmed that T N is 3.5 K. In addition, we have first observed two surprising results. Firstly, a shoulder was observed in the vicinity of 2 K in addition to the sharp peak at T N corresponding to the antiferromagnetic phase transition in the high-resolution measurement of the low-temperature specific heat. Secondly, the anomaly of the AC magnetization at T N depends to the magnetic field direction. We have clearly observed the anomaly of the AC magnetization at T N when the AC magnetic field orientation is parallel to the c-axis, whereas we have observed no anomaly of the AC magnetization at T N when the AC magnetic field orientation is perpendicular to the c-axis. These results clarify that our Er5Ir4Si10 single crystal is a quasi-two-dimensional antiferromagnet and has no three-dimensional magnetic structure of the Er3+ local moments. However, we have observed a peak of the AC magnetization around 2 K when the AC magnetic field orientation is perpendicular to the c-axis. This temperature corresponds to that at which a shoulder is observed in the measurement of the low-temperature specific heat. Furthermore, we have observed no frequency dependence of the AC magnetization which is ordinarily observed in the spin glass state. This result means that there is no disorder in our Er5Ir4Si10 single crystal because the crystal structure of Er5Ir4Si10 has the tetragonal crystal structure in which the octagons of Er3+ ions are stacked. In addition, both tetragons and octagons of Er3+ local moments have no magnetic frustration. At last we can conclude that both the shoulder of the low-temperature specific heat in the vicinity of 2 K and the peak of the AC magnetization around 2 K, which is only observed when the AC magnetic field orientation is perpendicular to the c-axis, correspond to the crystalline-electric-effect in the plane which is perpendicular to the c-axis of the tetragonal crystal structure. © 2008 Elsevier B.V. All rights reserved

K_<0.30>MoO_3の狭帯域雑音の低温での研究

金沢大学理学部本科研費が交付後、昭和62年10月に東京大学から岩手大学へ転任になり、その後再度岩手大学から金沢大学に、昭和64年の1月に転任することになり、本研究にじっくりと取りくむことが困難であった。しかし、金沢大学において研究テ-マを遷移金属カルコゲナイドの電荷密度波転移と超電導転移の相関とすることにより、わずかながらであるが論文として公表出来るような実績をあげることが出来た。その内容は平成元年度の研究実績の概要のところに記しておいたので、ここでは述べないことにする。転任につぐ転任の中で学術論文として公表出来るような研究成果を上げることは非常に苦労が多い。また転任ごとに研究テ-マに苦しみを味わった。今後はじっくりと、研究に励みたいと思っている。現在興味を持っている研究分野は超低温領域での物性であり、希釈冷凍機の購入を考えている。その準備段階として、高エネルギ-研の放射光実験施設の低温ワ-キンググル-プに属し、希釈冷凍機を用いた超低温X線回折のグル-プに参加し、非常に良いデ-タを得ている。この結果は今年(1990年)の8月にイギリスのサセックスで開催されるLT19で発表される予定である。また、超低温領域での中性子線回折にも興味をもち、現在勉強中である。海外留学か国内留学で中性子線回折の出来る共同利用施設のグル-プに属し、超低温でのX線回折同様に国際会議で発表できるような良い仕事をしたいと考えている。I have investigated the superconductivity transition in a layered transition-metal dichalcogenide 2H-Tas_2 by means of measuring electrical resistance down to 10 mK. We observed one which is highly sensitive to the current for the measurement of the electrical resistance. In addition the current-dependent- electrical resistance is clearly observed at 1.4 and 4.2 K respectively. This current-dependency is for the first time reported on this material. The physical origin is discussed in terms of the distribution of the superconductivity transition temperature within the specimen.研究課題/領域番号:62540230, 研究期間(年度):1987 – 1989出典：研究課題「K_MoO_3の狭帯域雑音の低温での研究」課題番号62540230（KAKEN：科学研究費助成事業データベース（国立情報学研究所）） （https://kaken.nii.ac.jp/ja/report/KAKENHI-PROJECT-62540230/625402301989kenkyu_seika_hokoku_gaiyo/）を加工して作

Direct Electron-Diffraction Evidence of Charge-Density-Wave Formation in NbSe3

金沢大学理学

Branching out in roots: uncovering form, function, and regulation

Root branching is critical for plants to secure anchorage and ensure the supply of water, minerals, and nutrients. To date, research on root branching has focused on lateral root development in young seedlings. However, many other programs of postembryonic root organogenesis exist in angiosperms. In cereal crops, the majority of the mature root system is composed of several classes of adventitious roots that include crown roots and brace roots. In this Update, we initially describe the diversity of postembryonic root forms. Next, we review recent advances in our understanding of the genes, signals, and mechanisms regulating lateral root and adventitious root branching in the plant models Arabidopsis (Arabidopsis thaliana), maize (Zea mays), and rice (Oryza sativa). While many common signals, regulatory components, and mechanisms have been identified that control the initiation, morphogenesis, and emergence of new lateral and adventitious root organs, much more remains to be done. We conclude by discussing the challenges and opportunities facing root branching research