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

有机导体中存在许多材料，如低尺寸表征阶段转换，例如CDW、SDW、自旋Peierls、某些磁性排序、超导电性，以及与强电子-电子交互有关的材料。我们在wide temperature range between 5 K and 300 K for the sample with the weight of 0. 3 mg的relative accuracy of 0. 1%to quantitatively discuss the above phase transitions。We succeeded in the measurements of 1 st order phase transition in the cooling and heating processes by a method based on DTA （Differential Thermal Analysis）。我们总结了以下结果：1。（DMe-DCNQI）_2铜系统·甲基基中自由度的双重度：系统化地执行了CH_3、CH_2D、CHD 2_和CD_3中的各种甲基基的特定热测量。在这些系统中，我们发现了异常特殊的热量，达到了自由的双重程度。我们在系统上确定了选定的特定热度。 ... More 在（DMe-DCNQI）_2Cu系统中的三甲基基。在equilibrium条件下，这些系统不会显示相位转换所诱导的尖锐峰值，但会显示系统中基于CH_2D和CHD_2的Schottky类型的特定热量。它们的能量计划仅由甲基基中的德国原子的位置决定。Et_2Me_2Sb系统的一种新类型的相位转换[Pd（dmit）_2]_2：在此转换中， Pd（dmit）^2。本地化magnetic moments s=1/2 change into neutral Pd（dmit）_2^0。和divalent Pd（dmit）_2^2-无自旋状态。我们已经研究了这个系统的热性能，并观察到了临界温度上的大驼峰，如相位过渡中的尖锐峰值和小半胱氨酸。在过渡区达到13 J/molK时，有机系统展示的收费排序过渡中的最大价值是最大的。我们发现旋转自由和晶格调制可以协同驱动这些新的类型相位转换。由θ-（BEDT-TTF）_2RbZn（SCN）_4的电荷排序诱导的神秘金属绝缘体转换：相位转换具有较大的温度歇斯底里，并在加热过程中表现出不同的峰值、大幅度和尖锐形状，以及冷却过程中的大驼峰。我们观察到异常的特定热量是由这个阶段的过渡引起的，并受到这个过渡的自由程度的讨论。Less（低）

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