准一维有机超导体(TMTSF)_2ClO_4的高精度温差电动势研究

Study on the high-resolution thermoelectric power of metallic state quasi-one-dimensional organic superconductor of (TMTSF)_2ClO_4 salt

测量了准一维有机超导体 (TMTSF) 2 ClO4 单晶a方向不同降温速率下的高精度温差电动势 (6— 2 80K) .高温下的温差电动势表现出线性行为 ,不能被正常的一维电子能带理论所解释 .在 2 4 0K左右观察到温差电动势斜率发生反常突变 .在 14 0K左右温差电动势向下逐渐偏离线性行为 ,这与 1D— 2D的维度渡越相关 .对阴离子有序—无序相变温度Ta(Ta=2 4K)附近的温差电动势结果与比热和电阻率的数据进行了比较 .对于极慢速降温的温差电动势 ,求导后可以看到相变的痕迹 .随着通过Ta 降温速率的增大 ,在Ta 之下的温差电动势数值出现了一个逐渐增大的整体抬高 .对此进行了讨论 .

We investigate the high-resolution thermoelectric power of Bechgaard salt (TMTSF) 2ClO 4 in temperatures between 6 and 280K for metallic state with different cooling rates through the anion-ordering transition T a=24K. There is a linear temperature-dependent thermoelectric power at high temperatures, which cannot be explained by conventional one-dimensional(1D) electron band theory. A sudden change of the slope at about 240K is observed for the first time. Below 140K, the curve deviates from linear behavior and goes down all the way through, which is attributed to a 1D—2D crossover. Comparing with the results of specific heat and resistivity with different cooling rates through the anion-ordering transition at 24K, no clear trace of anion-ordering transition can be spotted in thermoelectric power by the slowest cooling process unless we take differentiation of the data and we found a gradual rise in thermoelectric power with increasing cooling rate through the T a for the first time. The influence of anion-ordering transition is discussed.