Thermodynamic Investigation of the Gap Structure and Electron Pair-Symnetry in Organic Superconductors

This研究项目aims at clarifying the structure of energy gap in the superconductive statesBEDT-TTF based organic superconductors through analyses of specific heat data. To get detailinformation on the ground state and the low-energy excitations from it我们在extremely low-temperature region below IK.我们已经improved a sample experiment at extremely low-temperature region below IK.我们已经做了一个样本cell for the therma -relaxation type calorimeter equipped with the dilution refrigerator atInstitute for Molecular Science. As a consequence，我们succeeded to reduce the heat capacity of addenda part down to about 0.1μJ/K at 1k，b：解系统κ-(BEDT-TTF) b：解系统κ- D22 b：解系统κ- D2X[X=Cu[N(CN) d - 22 d - 2]Br，Cu(NCS) - D22 - D2],we have discussed the temperature dependence of specific heat and magnetic fieldsdependence of electronic specific-heat coefficientγ up to 10t，也可以discuss the residual γ* term in the superconductive state. the results suggestthat the gap-structure of this system可以explained with the frame of line-nodes picture ofwave superductors . It is however to be mentioned that the γ(H) curves of both salts show a kinkaround 2 t,它通常与这些材料的vortex states .我们已经去了关于这些材料的信息。the magnetic fields dependence of this γ in order to clarify the pairing nature and vortex state in者。

This research project aims at clarifying the structure of energy gap in the superconductive states of BEDT-TTF based organic superconductors through analyses of specific heat data. To get detail information on the ground state and the low-energy excitations from it, we performed the experiment at extremely low-temperature region below IK. We have improved a sample cell for the thermal-relaxation type calorimeter equipped with the dilution refrigerator at Institute for Molecular Science. As a consequence, we have succeeded to reduce the heat capacity of addenda part down to about 0.1μJ/K at 1K, which is satisfactory small to get enough resolution. For the system of κ-(BEDT-TTF)ィイD22ィエD2X [X=Cu[N(CN)ィイD22ィエD2]Br, Cu(NCS)ィイD22ィエD2] ,we have discussed the temperature dependence of specific heat and magnetic fields dependence of electronic specific-heat coefficient, γ up to 10T and also discuss the residual γ* term in the superconductive state. The results suggest that the gap-structure of this system can be explained within the frame of line-nodes picture of d-wave superconductors. It is however to be mentioned that the γ(H) curves of both salts show a kink around 2T, which may be related to the vortex states of these materials. We are going to further inquire into the magnetic fields dependence of this γ in order to clarify the pairing nature and vortex state in detail.