1995 Fiscal Year Final Research Report Summary
Design and Synthesis of Two-Dimensional Organic Conductors
| Project/Area Number |
06640469
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
固体物性Ⅱ(磁性・金属・低温)
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| Research Institution | The University of Tokyo |
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Principal Investigator |
HASEGAWA Tatsuo The University of Tokyo, College of Arts and Sciences, Research Associate., 教養学部, 助手 (00242016)
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| Co-Investigator(Kenkyū-buntansha) |
KAGOSHIMA Seiichi The University of Tokyo, College of Arts and Sciences, Professor, 教養学部, 教授 (30114432)
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| Project Period (FY) |
1994 – 1995
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| Keywords | Molecular Conductors / Charge Transfer Complex / BEDT-TTF / TCNQ derivative / Band Filling Control / Antiferromagnet |
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| Research Abstract |
The advantage of studying the title system is that the acceptors can be designed to have various LUMO levels by chemical modification, which enables us to tune the filling of 2D ET HOMO band. Another notable feature is the existence of local spins on anion radicals, which have the possibility of modulating the 2D conduction layrs.
As a first step of this strategy, we chose TCNQ and its fluorinated derivatives, and succeeded in synthesizing (ET) (FnTCNQ), where n=0,1,2,4. Among these, crystals of (ET) (F1TCNQ) display metallic behavior down to 2K.This is the first ET-based two-component system preserving metallic down to 2K.We note that the magnetic susceptibility of (ET) (F1TCNQ) does not show simple Pauli-paramagnetic behavior, but exhibits Curie-like enhancement with decreasing temperature. In (ET) (F2TCNQ) and (ET) (F4TCNQ), a novel type of mixed-stack CT crystals were obtained. They undergo anti-ferromagnetic transition at TN=30K and 14K.
These results indicate that neither the Peierls nor spin-Peierls instability to nonmagnetic phases occurs both in two-component system of (ET) (FnTCNQ). Intercolumnar contact of ET molecules plays a crucial role to suppress the 1D instabilities of acceptor columns. Unusual properties of electrical, magnetic, and optical properties of (ET) (FnTCNQ) were clarified.
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