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2017.10.03    文献調査

2017.09.19    予聴会

2017.09.12    予聴会

2017.09.05    文献調査

2017.07.25    文献調査

2017.07.18    文献調査

2017.07.11    中間報告(藤山、川椙)

2017.07.04    中間報告(大島、Kim、Lee)

2017.06.27    中間報告(崔、磯野)

2017.06.20    "有機超伝導体の超伝導対称性に関する熱的研究"  今城 周作氏(大阪大学 理学研究科 中澤研究室 D3)
超伝導状態では電子が引力によってクーパー対と呼ばれる電子対を形成している。従来型超伝導ではその引力の起源が電子ー格子相互作用だとわかっているが、有機物における超伝導をはじめ、多くの超伝導ではその引力の詳細な起源が分かっていない。その起源を知るためには引力相互作用を強く反映した超伝導ギャップ関数の決定が重要であるが、有機超伝導体においては実験的難しさからあまり研究は進んでいない。
本研究では状態密度を反映した電子熱容量を測定することで低エネルギー励起構造を検出し、ギャップ関数について議論している。またギャップ関数の正確な決定には波動関数の軌道だけではなく位相に関する情報も必要なため、磁場中角度分解熱容量測定という手法によってギャップ関数の異方性も検出し、正確なギャップ関数の決定を行っている。
セミナーでは高感度熱測定手法の開発やdimer-Mott系有機超伝導体の測定結果などを紹介する。

2017.06.13    "Microscopic Investigations of Solid / Liquid Interfaces Using Electrochemical Scanning Probe Microscopy"  横田 泰之博士(理研 Kim表面界面科学研究室 研究員)
Since Volta invented the voltaic pile late in the eighteenth century, electrochemistry has been one of the most important fields of study not only for academia but for industry. For instance, some parts of thermodynamics and kinetics chapters in the textbook of physical chemistry were developed by electrochemistry.
By the virtue of the thermodynamics, there is a general consensus concerning the fundamental aspects of electrolyte / electrode interfaces [1]. Although classical models can explain the electrochemical measurements to some extent, the macroscopic theory and measurements do not provide molecular scale pictures of the electrolyte / electrode interfaces.
In this seminar, microscopic structures of ionic liquid / solid interfaces revealed by electrochemical AFM (EC-AFM) will be discussed with respect to the device performance of electric double layer transistors [2]. Then, ongoing studies of electrochemical interfaces using (EC)-STM, related to Pioneering Project, will also be presented.
[1] A. J. Bard, L. R. Faulkner, “Electrochemical Methods 2nd Edition”, John Wiley & Sons (2000).
[2] Y. Yokota et al., Chem. Commun. 46, 8627 (2010), Chem. Commun. 49, 10596 (2013), Appl. Phys. Lett. 104, 263102 (2014), Phys. Chem. Chem. Phys. 17, 6794 (2015), Appl. Phys. Lett. 108, 083113 (2016).

2017.05.30    文献調査

2017.05.23    文献調査

2017.05.09    "Peculiar Paramagnetic Phase Adjacent to Superconducting Phase in Lambda-(BEDT-STF)2GaCl4"  南舘 孝亮博士(北海道大学 理学研究院 低次元電子物性研究室 博士研究員)
The organic quasi-two-dimensional conductor lambda-(BETS)2GaCl4 shows the superconducting (SC) phase below Tc=5.5 K. To clarify the adjacent phase of the SC phase in lambda-(BETS)2GaCl4 and discuss the origin of this phase, we have measured the electrical resistivity under pressure and the magnetic properties at ambient pressure in lambda-(STF)2GaCl4 (STF = bis(ethylenedithio)diselenadithiafulvalene), which was expected to be placed at the negative pressure region of the lambda-(STF)2GaCl4.
At first, we found the SC phase above 1.2GPa. We also found that the ground state of the STF salt at ambient pressure is the insulating phase without any ma gnetic ordering. Accordingly, the phase neighboring the SC phase is the non-AF-ordered paramagnetic insulating (PMI) phase.
Remarkably, in this PMI phase, the temperature dependence of the spin susceptibility obeys to the two-dimensional AF Heisenberg model with the regular triangle lattice. This is the typical behavior of the spin-liquid system. In the seminar, to explain the peculiar spin-liquid-like behavior in lambda-(STF)2GaCl4, we discuss the relation between the charge disproportionation and the geometry of the spin-interaction.

2017.05.02    昨年度年間報告および今年度計画(藤山、大島、李)

2017.04.25    昨年度年間報告および今年度計画(崔、藤山)

2017.04.18    昨年度年間報告および今年度計画(川椙、磯野)、一般公開議論

2017.04.13    "Symmetry Breaking Characteristic of Tight Dimerization in Antiferromagnetic Molecular Solid"  山本 貴博士(愛媛大学 理工学研究科 固体物理化学研究室 准教授)
Antiferromagnetic state of β'-Me4P[Pd(dmit)2]2 has been known as the obtuse and isosceles triangular lattice consisting of tight dimers with S = 1/2. Vibrational spectroscopy focused on electrical densities of C=C double bonds revealed symmetry breakings in lattice and molecule, which are discussed from the viewpoint of molecular orbitals specific to the tight dimerization.