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2018 Fiscal Year Final Research Report

Synthesis of new superconductors via the co-intercalation of metal and organic molecules

Research Project

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Project/Area Number 16K05429
Research Category

Grant-in-Aid for Scientific Research (C)

Allocation TypeMulti-year Fund
Section一般
Research Field Condensed matter physics II
Research InstitutionTohoku University

Principal Investigator

NOJI Takashi  東北大学, 工学研究科, 助教 (50180740)

Project Period (FY) 2016-04-01 – 2019-03-31
Keywords超伝導 / インターカレーション
Outline of Final Research Achievements

We have succeeded in synthesizing a new intercalation compound with large interlayer spacing between neighboring Fe layers and the superconducting transition temperature Tc = 39 - 45 K via the co-intercalation of alkali metal and ethylenediamine or phenethylamine into FeSe with Tc = 8 K. We have concluded that the pairing mechanism in the FeSe-based superconductors is due to the spin fluctuation and the increase in Tc via the co-intercalation is attributed to the enhancement of the spin fluctuation on account of the improvement of the Fermi-surface nesting.
On the other hand, we have succeeded in synthesizing new superconductors via the co-intercalating Li or alkaline earth metal and organic molecules in transition metal dichalcogenide MoSe2 and TiSe2. We have concluded that the appearance of superconductivity in these materials is due to the increase of the electronic density of states at the Fermi level and the enhancement of the electron phonon interaction by the phonon-softening.

Free Research Field

超伝導

Academic Significance and Societal Importance of the Research Achievements

本研究は、層間に金属と有機分子をコインターカレート(共挿入)することにより、キャリア濃度と次元性を変化させた多くの新規超伝導体を合成し、その物性を調べたものである。その結果、超伝導発現機構がスピンの揺らぎであるFeSeは、二次元化によりフェルミ面のネスティングが向上し、超伝導転移温度Tcが大きく上昇した。また、電子格子相互作用が超伝導発現に寄与している遷移金属ダイカルコゲナイドでは、二次元化によるTcの上昇は小さく、キャリア濃度にTcは依存することが分かった。
このように、超伝導発現機構が異なる物質に対するコインターカレーション効果を調べた研究は皆無であり、学術的意義は大きいと考えている。

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Published: 2020-03-30  

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