ANOMALOUS THERMAL-EXPANSION OF THE ORGANIC SUPERCONDUCTOR KAPPA-(BEDT-TTF)2CU[N(CN)2]BR

被引：54

作者：

KUND, M ^{[1
]}

MULLER, H ^{[1
]}

BIBERACHER, W ^{[1
]}

ANDRES, K ^{[1
]}

SAITO, G ^{[1
]}

机构：

[1] KYOTO UNIV,FAC SCI,DEPT CHEM,KYOTO 606,JAPAN

来源：

PHYSICA B | 1993年 / 191卷 / 3-4期

关键词：

D O I：

10.1016/0921-4526(93)90085-K

中图分类号：

O469 [凝聚态物理学];

学科分类号：

070205 ;

摘要：

High-resolution thermal expansion measurements on single crystals of the organic superconductor kappa-(BEDT-TTF)2Cu[N(CN)2]Br were performed along all three principal directions in the temperature range from 4 to 300 K by means of capacitive dilatometry. Large anisotropies were observed which originate in the layer-type structure and the orthorhombic symmetry of this compound. At 80 K an anomalous and pronounced increase of the orthorhombic distortion of the conducting a-c plane is seen which correlates. together with a small observed thermal hysteresis, with an anomaly in the electrical resistivity. Here, the volume expansion coefficient beta shows two subsequent jumps of approximately the same size (DELTAbeta = (22 +/- 4) x 10(-6) 1/K), but of opposite sign. We assume that a phase transition occurs at this temperature. A possible explanation for this is the interaction of donor libration modes with the polymeric anion through their terminal ethylenes via hydrogen bonds, leading in effect to an ethylene order-disorder transition.

引用

页码：274 / 280

页数：7

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