Thermal Study of phase transition for π-d organic conductor under pressure

π-d有机导体压力下相变的热研究

基本信息

批准号：
15340123
负责人：
NISHIO Yutaka
金额：
$ 10.43万
依托单位：
Toho University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2003
资助国家：
日本
起止时间：
2003 至 2006
项目状态：
已结题

项目摘要

Many materials in organic conductor undergo low dimensional characteristic phase transitions, for example, CDW, SDW, spin-Peierls, some magnetic ordering, superconductivity and so on with strong electron-electron interaction. We have developed specific heat measurement system in the wide temperature range between 5K and 300K for the sample with the weight of 0.3mg with relative accuracy of 0.1% to quantitatively discuss the above phase transitions. We succeeded in the measurements of 1st order phase transition in the cooling and heating processes by a method based on DTA (Differential Thermal Analysis). We summarized following results.1. (DMe-DCNQI)_2Cu system・Deuterium degrees of freedom in methyl basis: Specific heat measurements are systematically performed for the systems having various methyl bases of CH_3, CH_2D, CHD2_and CD_3. In these systems, we discovered the anomalous specific heat due to deuterium degrees of freedom. We systematically clarified the specific heat of selectiv … More ely deuterated methyl bases in the (DMe-DCNQI)_2Cu system. Under equilibrium condition, these systems do not show the sharp peak induced by the phase transition, but exhibit the Schottky type specific heat in the systems having CH_2D and CHD_2 bases. Their energy schemes are determined only by the position of the deuterium atom in the methyl bases.2. A new type phase transition for the system of Et_2Me_2Sb[Pd(dmit)_2]_2: In this transition, Pd(dmit)^2. having localized magnetic moments s=1/2 change into neutral Pd(dmit)_2^0. and divalent Pd(dmit)_2^2-spin-less states. We have studied the thermal properties of this system and observed a broad hump above critical temperature as well as the sharp peak with small hysteresis in the vicinity of the phase transition. Resulting total entropy absorbed around the transition region reaches to 13J/molK, which is largest value in the organic systems exhibiting charge ordering transitions. We found that spin freedom and lattice modulation cooperatively drive these new type phase transition.3. Mysterious metal-insulator transition induced by a charge ordering for θ-(BEDT-TTF)_2RbZn(SCN)_4: These anomalies at the phase transition have large temperature hysteresis and show different shapes of the peak, huge and sharp peak in heating process and broad hump in cooling process. We observed anomalous specific heat caused by this phase transition and discussed quantitatively degrees of freedom of this transition. Less

有机导体中的许多材料都会发生低维特征相变，例如CDW、SDW、自旋-Peierls、一些磁有序、超导等具有强电子-电子相互作用的材料，我们开发了宽温度范围内的比热测量系统。我们以0.3mg的样品在5K到300K的温度范围内，以0.1%的相对精度定量讨论了上述相变的测量。我们总结了基于DTA（差热分析）的方法的冷却和加热过程（DMe-DCNQI）_2Cu体系·甲基氘自由度：系统地对具有各种体系的比热进行了测量。在这些系统中，我们发现了由氘自由度引起的反常比热。 (DMe-DCNQI)_2Cu 体系中选择性氘代甲基碱的含量在平衡条件下，这些体系没有表现出由相变引起的尖峰，但在具有 CH_2D 和 CHD_2 的体系中表现出肖特基型比热。它们的能量方案仅由甲基碱基中氘原子的位置决定。2． Et_2Me_2Sb[Pd(dmit)_2]_2：在此转变中，局域磁矩 s=1/2 的 Pd(dmit)^2 变为中性 Pd(dmit)_2^0 和二价 Pd(dmit)_2^2。我们研究了该系统的热性质，并观察到临界温度以上的宽峰以及相变附近具有小滞后的尖峰。过渡区周围吸收的总熵达到13J/molK，这是表现出电荷有序转变的有机系统中的最大值。我们发现自旋自由度和晶格调制共同驱动了这些新型的金属-绝缘体转变。由 θ-(BEDT-TTF)_2RbZn(SCN)_4 的电荷排序引起：相变时的这些异常具有很大的温度滞后并表现出不同的形状我们观察到了这种定量相变引起的异常比热，并讨论了这种转变的自由度。

项目成果

期刊论文数量（25）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

K.Kajita: "Organic semiconductors with extremely narrow energy gap"Synthetic Metals. 133-4. 95-97 (2003)

K.Kajita：“具有极窄能隙的有机半导体”合成金属。

DOI：
发表时间：
期刊：
影响因子：
0
作者：
通讯作者：

A new organic superconductor β-(meso-DMBEDT-TTF)_2PF_6

新型有机超导体β-(meso-DMBEDT-TTF)_2PF_6

DOI：
发表时间：
2004
期刊：
Chem.Commun.
影响因子：
0
作者：
H.Okamoto;et al.;H.Suzuki et al.;S.Kimura et al.
通讯作者：
S.Kimura et al.

Pyrazino-fused organic conductors CnDTP-TTF and CmDTP-STF(n=5,6)

吡嗪稠合有机导体 CnDTP-TTF 和 CmDTP-STF(n=5,6)

DOI：
发表时间：
2005
期刊：
Synthetic Metals 153
影响因子：
0
作者：
T.Mochida;T.Mochida;Shigeharu. Sugawara;Naoya Tajima;Riki Jindo;Shigeharu.Sugawara;Naoya Tajima;Riki Jindo;Riki Jindo;Tomoyuki Mochida;Naoya Tajima;Miyuki Suto;H.Suzuki;S.Kimura
通讯作者：
S.Kimura

Crystal structures and electrical conductivities controlled by CH/n interactions

CH/n 相互作用控制的晶体结构和电导率

DOI：
发表时间：
2004
期刊：
J.Phys.IV France 114
影响因子：
0
作者：
K.Waku;H.Okamoto;et al.;S.Kimura et al.
通讯作者：
S.Kimura et al.

Control of electronic state in the 2D hydrogen-bonded system : β-(CnDT-EDO-TTF)_s(PF_6)_x (n=5,6,7,8)

二维氢键体系中电子态的控制：β-(CnDT-EDO-TTF)_s(PF_6)_x (n=5,6,7,8)

DOI：
发表时间：
2004
期刊：
Synthetic Metals 144
影响因子：
0
作者：
T.Mochida;T.Mochida;Shigeharu. Sugawara;Naoya Tajima;Riki Jindo;Shigeharu.Sugawara;Naoya Tajima;Riki Jindo;Riki Jindo;Tomoyuki Mochida;Naoya Tajima;Miyuki Suto;H.Suzuki;S.Kimura;Naoya Tajima;Shinya Kimura;Hideaki Suzuki
通讯作者：
Hideaki Suzuki