Thermodynamic Investigation by Heat Capacity Measurements of k-type Dimer-Mott Organic Compounds with Chemical Pressure Tuning
Thermodynamic Investigation by Heat Capacity Measurements of k-type Dimer-Mott Organic Compounds with Chemical Pressure Tuning
复制标题
通过化学压力调节 k 型二聚体-莫特有机化合物的热容测量进行热力学研究
DOI：
10.1142/s0217979218400246
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发表时间：
2018
影响因子：
1.7
通讯作者：
Hiroki Akutsu and Yasuhiro Nakazawa
中科院分区：
文献类型：
--
作者：
Yuki Matsumura;Shusaku Imajo;Satoshi Yamashita;Hiroki Akutsu and Yasuhiro Nakazawa
通过对部分氘代配体-（d[n，n] BEDT-TTF）2Cu[N（CN）2]Br的热容测量，对（BEDT-TTF）2X型二聚-Mott体系Mott边界附近的物理性质进行了热力学讨论.我们比较了在快速冷却和缓慢冷却条件下获得的d[2，2]、d[3，3]和d[4，4]化合物（如图1所示定义）的热容的温度依赖性。d[2，2]化合物的热容在25 ~ 50 K范围内随冷却速率的变化而变化，而其它化合物的热容随冷却速率的变化不大。d[2，2]和d[3，3]的化合物在很靠近Mott边界处的CT中显示出特殊的驼峰结构，这与在一级相界附近存在一种晶格不稳定区有关。根据Mott边界在低温区具有特殊圆化的相图，讨论了反常区的温度和化学压力依赖性。
Thermodynamic discussion on the physical properties around the Mott boundary of the dimer-Mott system of-type (BEDT-TTF)2Xsystem, where BEDT-TTF is bis(ethylenedithio)tetrathiafulvalene andXdenotes monovalent counter anions is performed by heat capacity measurements of the-(d[n,n] BEDT-TTF)2Cu[N(CN)2]Br of which donor molecules are partially deuterated. We compare temperature dependences of heat capacity of d[2,2], d[3,3] and d[4,4] compounds (defined as shown in Fig. 1) obtained in rapidly cooled and slowly cooled conditions. While the heat capacity of d[2,2] compound shows cooling rate dependence with the slight change of the absolute valuesCpbetween 25 K and 50 K, the temperature dependences of the other compounds do not give drastic change by changing the cooling rate. The compounds of d[2,2] and d[3,3] located very close to the Mott boundary show peculiar hump structure in theCTthat is related to the existence of a kind of lattice instability region around the first-order phase boundary. The temperature and chemical pressure dependences of the anomalous region are discussed in terms of the phase diagram in which the Mott boundary has peculiar rounding at low-temperature region.